It does the same thing. It compress the hammer springs. The wheel have some notch, as you turn higher in the number wheel, it compress the spring more and more. Thats how you get more power. On mk1 and mk2, you use a hex key to turn on the nut left of the wheel, as you increase it will also compress the spring more and more. Giving you more power. On m3, they change it a dial, so you turn the dial to increase tension on the spring. There is a limit on how much you can compress the spring with both the spring adjustment and the wheel. Too much and the gun won't cock.