Questions and Answers for ScubaPro MK2 Plus DIN Regulator - 1st Stage Only:
What is the difference between the MK2, MK17, and the MK25?
Bill (Certified Scuba Instructor at Scuba.com)
The MK2 is a standard unbalanced first stage. The MK 17 is seal diaphragm, balanced first stage and the MK 25 is a piston balanced first stage. The MK 25 is the highest performing regulator of the three.