The Griffin Armament Revolution Fixed Barrel Spacer replaces the spring on Revolution silencers to lock the piston from traveling when the suppressor is used on a fixed barrel firearm. The spacer should only be used on a fixed barrel firearm. Additionally the piston with spring should only be used on non fixed barrel firearms as using a sprung silencer on a fixed barrel firearm will cause damage to the suppressor.Note: THE FIXED BARREL SPACER IS RATED UP TO .300BLK SUBSONIC. USE OF THIS PRODUCT ON SUPER SONIC, CENTERFIRE RIFLE CALIBERS WILL CAUSE DAMAGE TO THIS PART AND POSSIBLY THE SILENCER AND IS NOT COVERED UNDER WARRANTY.Compatible with: Optimus, Resistance, and Revolution series of suppressors.