It has what is probably the hardest name to remember of any regulator, but the Scubapro MK25 AFSA/S600 is the answer to the prayers of those who wish to take their regulators as carry-on luggage on planes but are stymied by the recent 6kg limit now imposed by many charter airlines.
     It gets its lighter weight by being made of a stainless steel/aluminium mix instead of the usual weightier chromed-brass.
     Scubapro had a previous foray with the all-aluminium MK20 Ultralight. I wrote of it in Diver Tests in 1998:
     It is a sad fact that technological advances can be painful for those brave enough to make them, and the MK20 Ultralight has its problems. Fragility is one... Another problem seems to be electrolysis. Two friends of mine who bought early examples of MK20ULs took them on trips to the Galapagos and to the Maldives. They are broken-hearted. The electrochemical interaction between the aluminium of the first stage and the different metal of the hoses screwed into them, united in the presence of salt water and tropical heat, has led to serious corrosion.
     The MK20 UL first stage sent to me by Scubapro is of a later batch. The black outer coating appears to be of a different, thicker material. There are also small washer-like discs between the port plugs and the main body of the regulator that stop over-tightening. I installed these with my direct feed and high-pressure hoses. The turret is also now enclosed in a plastic cage to prevent the coating getting knocked.
     Despite my optimism and Scubapros attempts at improvements, the MK20 UL did not seem to last long in the market place. Scubapros ill-fated adventure must have taught its designers a lot.
     Their latest lightweight regulator design, the MK25 AFSA, is also their best attempt yet at a high-performance regulator for use in cold, fresh water.
     Scubapro has used stainless steel in the parts that need the strength. I hope there will be no electrolysis between the steel and the aluminium of the main body of the regulator. There are plastic spacers between the port plugs and ports, presumably to stop them welding together. I couldnt transfer these to the chromed-brass ends of the hoses that I wanted to screw in, so I asked Scubapro to send me some extras. It seemed obvious.
     Of course, I never had the regulator in my possession long enough to find out if there was a serious corrosion-by-electro-lysis problem, but I did sit the regulator in the brine tank of my domestic water-softener for a week without obvious ill-effect.
     I would still take the precaution of removing any chromed-brass tipped auxiliary hoses before I put it away in storage for any lengthy period, or find a supply of plastic spacers.
     I had hoped that the ones on the port plugs might have been interchangeable but they were not. So, sadly, I am unable to tell you what you really need to know.
     The MK25 first stage is a development of that otherwise very successful MK20, and the company has addressed the risk of freeze-ups by including larger holes to allow warming water (warmer than the air from your tank, anyway) to pass around the works chilled by the passage of depressurised air.
     External fins add greater heat-sink qualities and discourage ice from creeping up the outside of the body of the regulator to obscure those vital holes.
     Scubapro also continues with its Thermal Insulation System, just as it does with all its current regulators. This uses materials and coatings for the moving parts that reduce the chance of sticking because of icing.
     Its very difficult to determine whether all this works perfectly. Im sure no regulator manufacturer in its right mind would guarantee that a valve could not fail due to severe cold conditions.
     I can say is that the unit is incredibly light.
     It also appears to be beautifully crafted, although one fellow- diver actually asked if it was made of plastic! Some will interpret that as its having a flimsy appearance.
     The S600 second stage is a delight to breathe from, and we have reviewed it several times before. It too is remarkably light, and small enough to be unobtrusive. It has the usual inhalation-resistance adjustment knob, and a dive/predive switch designed to prevent exponential free-flows at the surface.
     Both are easily accessed with a gloved hand, though neither had much discernible effect in the water.
     The small exhaust-T meant that some distracting bubbles did come up within my field of vision, but not as badly as happens with some other compact regulator designs.
     The regulator certainly gave me as much air as I needed, and often in a gushing rush if I heaved too heavily.
     As found in the past, it was impossible to reassemble the second stage easily after a quick look inside the front to peer at the mechanism. It seemed very difficult to line up everything properly to insert the final locating pin. So leave it alone.
     Well done again, Scubapro. I just wish I could finally decide if its worth spending the extra ton over and above the cost of the standard model, just for the loss of a few grams of weight in the bag. Probably not!
The Scubapro MK25 AFSA/S600 costs £449.
  • Scubapro UK 01256 812636, www.scubapro.co.uk

  • Divernet
    + Scubapros top-performing first stage in lightweight materials

    - Does the extra cost match the benefit
    - Longevity remains to be proved