The PRO Compensator was designed to be compatible with the G19 but will fit and function on other 9mm Glock models and will generally cycle with standard 9mm ammunition without any modification to the guide rod or recoil spring. Due to it's compact design, when installed on a G19 with a ZEV threaded barrel, it has the same overall length as a G34 slide and is compatible with most G34 Holsters.