Zev 9MM PRO Compensator V2 ( COMP-PRO-V2-B) was designed to reduce muzzle climb and felt recoil which would enhance the performance of your GLOCK pistols. The updated V2 compensator has contoured porting, an enlarged guide rod channel, and a new mounting system. The ZEV V2 PRO Compensator will work on all 9mm GLOCK models with a 1/2x28 thread pitch. When mounted on a G19, the overall length is the same as a standard G34 and will fit in most G34 holsters. The V2 PRO Compensator will generally function with standard power 9mm ammunition and factory recoil assemblies but best performance will be obtained through matching the recoil spring weight to your particular pistol and ammunition.