Healthways was known as the economy regulator company of its day. In August of 1962 Healthways wanted to create a professional line of equipment and hired Dick Bonin and Gustave Della Valle to create this line.  They chose the name SCUBAPRO for this upgraded or professional line.

Healthways was in financial trouble and declared bankruptcy on December 26, 1962, only four months after hiring Dick and Gustave.  Dick and Gustave decided to begin their own company and purchased the name SCUBAPRO from Healthways for $1.00. 

 In 1974 Dick sold the company to the Johnson’s Wax Company for $11 Million.  Johnson's Wax is now called the S. E. Johnson Company and the outdoor division is Johnson Outdoors.  Dick Bonin stayed with SCUBAPRO as President of the company until his retirement in 1997.

 FIRST STAGE REGULATORS

The MK 1 was not the first regulator that was produced by SCUBAPRO.  It was developed during the time when Dick Bonin and Gustave Della Valle were working with Healthways. The piston is a balanced flow-thru design that is still used today.

This regulator was on the market from 1964-1977. The MK 1’s performance at deeper depths is superior to the MK 2.  It has a rounded bottom with a single low pressure port and one high pressure port.  The yoke is the smallest of the three yoke sizes that SCUBAPRO has offered.  This small yoke design should only be used with a tank that holds a maximum of 2250 PSI.

The MK 2 is actually the first Regulator that was purely SCUBAPRO.  It was introduced in 1963, the first year of SCUBAPRO, and is still offered now with only a few modifications.

This regulator is without a doubt the most dependable first stage in the world.  It is a standard piston design.  The original, 1963-1971, has a small yoke with a wing nut and a rounded bottom.  It had two low pressure ports and one high pressure port. 

The second generation, 1972-1977, has a flat bottom, with the small yoke, wing nut and two low pressure ports and one high pressure port. 

The third Generation, 1978-1980, also has a flat bottom, three low pressure ports, one high pressure and S.P.E.C. ambient pressure ports. The S.P.E.C. cap can be identified by very small ambient port holes. There was an optional S.P.E.C. rubber boot available. 

The fourth generation was available from 1993-1995.  The S.P.E.C. cap had now been removed.  It has three low pressure ports, one high pressure port, large yoke and the wing nut has been replaced by a black knob with SCUBAPRO molded into it. 

The fifth generation, 1996-1997, has four low pressure ports, one high pressure port, large yoke, and black knob with a sticker that said MK 2 on it and a rubber boot bumper on the cap. 

The sixth generation, 1998-present, has a MK 2 Plus sticker and a rubber bumper over the regulator cap it also has a matt finish.  There was also an accessory called the environmental cap for the early MK 2 first stages.  This cap replaces the standard cap for the MK 2 and is bulbous in appearance. 

The MK 200 is a slightly different version of the MK 2.  It has a piston head that is slightly larger than the MK 2.  It was on the market from 1988-1992.  The MK 200 has three low pressure ports, one high pressure port, a large yoke and black knob that have a MK 200 sticker.  There were two versions.  The first version, 1988-1991, has an S.P.E.C. cap. An optional rubber S.P.E.C. boot was offered for this regulator and would also fit the end cap of a MK 2 first stage.  In 1992 the S.P.E.C. cap was removed.

The MK 3 was available from 1964 – 1987 and can be considered to be a baby MK2.  The main identifier is internally.  The piston head of the MK 2 is about the size of a quarter and the MK 3 piston head is the size of a nickel. 

The first generation, 1964-1965, has a small yoke, wing nut, flat bottom, two low pressure ports and one high pressure port.  The second generation, 1966-1981, is the same except the bottom is now rounded.  The third generation, 1982-1987, has three low pressure ports, one high pressure port, a flat bottom, large yoke, wing nut and an S.P.E.C. cap.

The MK 4 did not exist as a first stage on its own.  It was sold in Europe as a combination MK 5 with the 108HP second stage.

The MK 5 revolutionized the first stage with its flow-thru piston design.  It was so popular that  it was on the market for 25 years, 1965-1990.

The MK 5 provided a consistent flow of air to the second stage at any depth.  It truly is the first high performance first stage regulator in the industry.  The MK 5 is the first regulator to offer the consumer a swivel.  It is also considered one of the most dependable first stages ever built.

The first of the MK 5’s, 1965-1977 has one high pressure port and two low pressure ports on the swivel and has a small yoke and wing nut.  The second generation, 1978-1979, is the same as the first with the exception of the addition of a four port low pressure swivel and a bit heavier yoke.  The third generation MK 5, 1980 only, added three modifications.  The first is an even heavier yoke and the second is the addition of an S.P.E.C. cap  All of the previous MK 5 regulators have an optional Environmental Cap for cold water diving that is bulbous in appearance.  The third modification is the addition of a second High pressure port. The fourth generation, 1981-1985, added a fifth low pressure port.  The fifth MK 5 first stage, 1988-1990, is the same as the fourth generation, but, it has a black knob with a sticker that says MK5 instead of a wing nut being added. 

A sixth version of the MK 5 was produced in Sweden for a short period of time.  This version had a totally different swivel and swivel retainer. 

In 1981 SCUBAPRO made an accessory that could be added to the first stage.  The device was called the "Sonic Adapter” and its purpose was to give the diver an audible alarm when their air dropped to around 600 PSI.  It was only made this one year. 

The MK 5 external design is the most copied by manufacturers around the world, yet they never achieved the performance that the original has.  The MK 5 is still being used by many divers to this day. 

The MK 6 is simply another version of the MK 5.  It was on the market from 1969-1972.  The only difference that it had from the MK 5 is that the yoke was pneumatically attached to the tank valve as opposed to the Yoke Screw.  The MK 6 had a swivel like the original MK 5 with two low pressure ports and one High Pressure port.  A second version of the MK 6 has a yoke nut and a beefier mid-sized yoke.  This new yoke design could be replaced with the standard yoke design if the consumer desired.

The MK 7 was available from 1971–1987 and has the most unique appearance of any SCUBAPRO regulator.  The MK 7 is the only SCUBAPRO regulator that has a fixed non-swivel yoke.  It is very large and heavy and has the feature of an audible alarm when your tank pressure dropped to around 600 PSI which could be adjusted to the individual divers needs.  When your air got to this point the regulator would vibrate to cause a honking sound.  This honking earned the regulators the nick name "The Honker”.  The piston of this first stage is exactly the same as the MK 5.  

There are three generations of the MK 7 and each can be identified by the size of the yoke.  The original, 1971-1977, has the small yoke. The second generation, 1978 only, has a medium size yoke and the third generation, 1980-1987 has the heaviest yoke.  All three generations have a wing nut, one high pressure port and two low pressure ports.

 The MK 8 is again another version of the MK 5.  It was on the market from 1979-1982.  There are three versions.  The primary difference from the MK 5 is that it did not have a swivel.  The first generation, 1979-1980 has a small yoke, wing nut, with one high pressure port and one low pressure port and the cap has a rounded appearance.  The second generation, 1980 only, has a rounded bottom with one low pressure port and two high pressure ports. The third generation, 1981 only, has a flat bottom, three low pressure ports and two high pressure ports.  We have not been able to locate a production model of this version.  It is pictured in the 1981 catalog, but no one seems to remember it actually making it to the market in the USA.  Please contact us if you have one of these regulators or any documented information on this MK 8.  The fourth generation, 1982 only, has 2 high pressure ports and 4 low pressure ports with an S.P.E.C. cap.  All of the MK 8 first stages have a wing nut. 

The MK 9 came onto the market in 1983 and was available to purchase through 1985.  This is a totally new design by SCUBAPRO.  The piston head is considerably smaller than the MK 5 piston head and the piston travels entirely in the regulator body.  You can tell the difference by the placement of the ambient ports. On the MK 5, the ambient ports are on the cap while the MK 9 has the ports on the regulator’s upper body and the MK 9 does not have a swivel The MK 9 has a large yoke, wing nut, five low pressure ports and two high pressure ports. 

The MK 10 is an upgraded version of the MK 9.  The difference is that a swivel was added to the MK 9.  It was available from 1984-1995. The first generation MK 10, 1984-1995, can be identified by the large yoke and a wing nut.  The second generation, 1988-1989, changed the wing nut to a knob with a sticker that said MK 10, which is common place today. The third generation, 1990-1994, the ambient ports were changed to the S.P.E.C.  An optional S.P.E.C. kit could be added so that an environmental silicone could be added to enhance the performance in colder water.  The kit came with a black rubber boot and environmental silicone.   

Many people confuse the MK 10 with the MK 5.  The sure fire way to distinguish them apart is the location of the ambient ports.  The MK 5’s ambient ports are located on the piston cap located in the center section of the regulator and the MK 10’s are located on the upper main body as it is in the MK9.  This regulator was paired with the world famous G250 second stage and became one of the most popular first stages in history.  All MK 10 regulators have two high pressure ports and five low pressure ports on its swivel.

The MK X, not MK 10, regulator was sold in Europe as a combination only.  The Mark X is a MK 10 first stage paired with a "balanced” 109 second stage.  In the USA this was known as the Balanced Adjustable.  It was sold as The MK X Dual Balanced regulator system.  This is marked on the metal cover of the second stage.

The MK 10 PLUS was a first step of transitioning first stage regulators from the MK 10 to the MK 20.  It was on the market from 1996-1997.  SCUBAPRO placed a bushing on the piston along with a silicone sleeve that assisted in making the piston more cold water proof. The MK10 Plus could handle tank pressures up to 4000 PSI.   The knife edge on the piston was also redesigned to a more rounded feel and the concave seat was replaced with a seat with a flat bottom.  The only external distinguishing items are that the yoke knob had MK 10 PLUS on the end cap and the seat retainer was satin chrome. 

The MK 10 Plus also had an optional Nitrox kit.  The Nitrox version has a Yellow sticker with green printing on the yoke knob, a green saddle between the yoke and the body and a yellow sleeve instead of the black that came on the original.  The MK 10 Plus, like the MK 10, had two high pressure ports and five low pressure ports on its swivel.

The MK 15 was originally designed to handle tank pressures up to 4000 PSI.  It has a new and larger piston head than the MK 10 or MK 10 Plus.  The MK 15 has small ambient ports, a matte finish, rubber sleeve located between the swivel and the piston cap, five low pressure ports, two high pressure ports, a large yoke and a yoke knob as opposed to a wing nut.   

There are only two versions of the MK 15 as it was only on the market from 1994-1995. The first version, 1994 only, can be identified by the seat retainer.  The first version, and the rarest, has a slot for an Allen key for removal of the seat retainer and the second version of the seat retainer has two pin holes.  The second version, 1995 only, also has an upgraded high pressure seat.  Both versions of the MK 15 have two high pressure ports and five low pressure ports on its swivel.

The MK 20 TIS was on the market from 1996 – 2001.  This new flow thru piston design with its large composite piston head and low friction bushings enhanced reactivity by reducing friction thereby improving the flow rate to over 300 cubic feet of air per minute.  This became the most high performance regulator in the entire dive industry.  The plastic bushing system insured that the piston would align perfectly each time the knife edge would strike the seat.  

The piston itself went through four modifications during its tenure.  The original piston had a single o-ring on the piston head with a low friction square shaped ring and an all stainless shaft with a rounded edge on the seating end.  The second piston was changed to a chrome plated brass with the tip remaining uncoated. The third modification is a full stainless steel piston head with a single o-ring held in between 2 square shaped low friction rings.  The fourth version is a composite head with two o-rings and a stainless shaft with an enlarged rounded edge creating a smaller surface contact area, but still retaining the rounded edge detail.   

The main spring also has a polyurethane coating to prevent ice crystals that may cling to the spring coils during cold water diving.  This was done as a means to prevent freezing up.  This system was called the "Thermal Insulating system” or T.I.S.   

There are three versions all coming on the market at the same time.  The Brass version, 1996-2001, has a matte finish with a rubber sleeve around the body, a black knob with black sticker with MK 20 written on it.  This version also has a black saddle with three slits in it.  This saddle was later replaced with a saddle that only has two slits after an upgraded yoke retainer was installed.   

The second version, 1996-1999, is a Nitrox regulator.  This regulator can be identified by the yellow sticker with MK 20 Nitrox printed in green on it, a green saddle and a yellow rubber sleeve on the body.  The first MK 20 Nitrox had a brass piston with a green piston head bushing.  The MK 20 Nitrox was oxygen cleaned.  SCUBAPRO stated that this oxygen cleaned regulator should never be used with 100% oxygen.  They also felt at this time that any SCUBAPRO regulator that is exposed to oxygen mixtures above 23.5% should be oxygen cleaned and compatible.   

The final version was the MK 20 UL for ultra-light.  It has a black body and the internal walls are polyurethane coated.  The original piston was also made of aluminum with Teflon coating on the shaft with the tip being uncoated.  The regulator body was made of anodized aluminum magnesium alloy Teflon coated.  The black body had two different looks; the black aluminum is the original, 1997-1999, and the brownish/black body came in 2000.  Like many of its predecessors, the MK 20 has two high pressure ports and five low pressure ports on its swivel. 

The MK 25 came into the market in 2002 and the first version was called the MK 25 T.I.S.  (Thermal Insulating System), 2002-2003.  It is made from brass and its appearance is very similar to the MK 20.  The primary change was the Seat retainer.  In the MK 20 it was removed with an Allen key and on the MK 25 it can only be removed with a socket.  In the center of this cap is an adjustment screw.  This adjustment screw enabled the technician to adjust the intermediate pressure of the first stage from the outside.  The MK 25UL, 2002 only, has a black aluminum body.  The MK 25’s Thermal Insulating System is exactly the same as the MK 20.   

The MK 25T, 2002-present, is mechanically the same as the MK 25 T.I.S.  It also appears the same.  The only difference is that the body is made of titanium instead of brass.  There are two versions of the MK 25T;  the first version, 2002-2003, had the cap design of the MK 25T.I.S. and the second version, 2004-present, had the finned cap design of the MK 25 AF.   

The MK 25 AF, 2004-present, added a finned cap.  These fins are designed to dissipate cold generated during pressure reduction and warm up the first stage to improve, even more, the anti-freeze characteristics of the MK 25.  The MK 25 SA, 2004-2006, which is again mechanically the same as the MK 25AF, has the swivel and seat retainer made of stainless and the body aluminum.  The MK 25 TI came on the European market in 2002.  This regulator is also mechanically the same as the MK 25 AF with a black aluminum body and a titanium swivel. In 2009 the MK 25AF came out with a new highly polished body instead of the matte finish.  It was only available in combination with the newly introduced A700 second stage. All MK 25 models have two high pressure ports with five low pressure ports located on its swivel.  In 2009 a highly polished version of this model was offered in combination with the new all metal A 700 second stage.

 THE BALANCED DIAPHRAGM REGULATORS

The MK 14 was on the market from 1998-2000.  This was SCUBAPRO's first ever diaphragm regulator.  SCUBAPRO decided to enter this market because there are many divers around the world, especially in Europe, that preferred this type of regulator for cold water diving.  The yoke knob was marked with a sticker stating that it is a MK 14 and it had two high pressure ports and 5 Low pressure ports on the swivel.

In 1999 the MK 18 was introduced and remained on the market through 2001.  The MK 18 is the first proprietary diaphragm design. The MK18 was a bit more high performance than the MK 14 and was offered in two versions.   

The first version 1999-2000, is the MK 18 UL and was black in color.  The second version, 2001 only, is the standard brass version. There are two different looks to the UL.  The first is a black body and cap and the second, 2001 only, has a brownish black coloration. The MK 18’s swivel is tapered down from the body, were as the MK 14’s swivel is beefier and about the same size as the regulator cap.  The yoke knob had a sticker indicating that it is a MK 18.  The MK 18 has two high pressure ports and five low pressure ports on its swivel.

The MK 16, another entry into the diaphragm regulator market, was on the market from 2001 through 2005.  In reality it was still being sold through 2009 as a special sale regulator with an upgrade kit installed and an R190 second stage attached.  The MK 16 has all the same internal parts as the MK18.  There were two versions the first, 2001-2003, had a large rubber cap over the regulator cap and the second version, 2004-2005, had a more compact rubber ring.  The MK 16 had two high pressure ports and four low pressure ports.

The MK11 along with the MK17 were brought to the market in 2006.  These diaphragm regulators were the first on the market that could be considered high performance.  These regulators could handle flow rates up to 250 cubic feet of air per minute.   

The MK11 is a very compact first stage with two high pressure ports and four low pressure ports.  The yoke knob has a sticker on it designating it as a MK11.  A titanium version was added in 2009.  SCUBAPRO Japan also introduced a MK11 T White in 2009.  This regulator is exactly the same as the USA version with the exception that the knob is white and the two boots on the regulator main body are also white.  This was paired with an S555 that has a white insert and a white Vinturi adjustment knob.

The MK17 is slightly different than the MK11 on the inside.  The major difference is the addition of a totally dry ambient chamber that is completely environmentally sealed ribbed end cap with a unique dual diaphragm system to read the ambient pressure.  The function of this cap is to keep out contaminated water and the ribs are designed to better dissipate cold generated during pressure reduction to make the MK 17 even more cold water proof.   The sticker also states that it is a MK17 and it also has two high pressure ports and four low pressure ports. 

The MK19 was introduced to the European market in 2007.  The MK19 is a MK17 that has a swivel containing five low pressure ports.  It was not available in the Americas.

 SPECIAL FIRST STAGE REGULATORS

The 24ct Gold Plated MK 10/G250 was produced in 1991 as a special promotional regulator.  There were only 300 produced commemorating the number one selling regulator in history.  

There were also several military version regulators produced over the years for the Italian Navy.  These regulators are all Black anodized chrome plated brass and came in combinations of the MK 5/109 and MK 5/Balanced Adjustable. 

The European market in 2007 introduced the MK2/295 Oxygen and the MK 25 S555 Oxygen.  These regulators are certified for use with 100% oxygen and can be easily distinguished from the standard models by the Green front covers on the second stages, green hose protectors, and green bumpers.  These regulators are EN 144.3 fitted and will not work in standard DIN 477 fitted tank valves.  In 2009 SCUBAPRO AMERICAS offered an upgrade kit for the MK 2 and the MK 25.