This is a ZEV Technologies Compensator known as the Pro Comp V2 chambered in 9MM, model COMP-PRO-V2-LH-B.
The ZEV V2 PRO Compensator was designed to enhance the performance of your Glock pistol by reducing muzzle rise and felt recoil. The V2 improves upon the original PRO Compensator with contoured porting" an enlarged guide rod channel" and a new mounting system which permits secure installation and removal without the need for thread locking compound. The ZEV V2 PRO Compensator was developed and optimized for use on the G19 but will fit and function on all 9mm Glock models with a corresponding threaded barrel. Due to its compact size" when installed on a G19 with ZEV threaded barrel" it has the same overall length as a G34 slide and is compatible with 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.
Features:
For 9mm Glock models
Can function with factory recoil assemblies
New mounting system