The Underworld Arms Mid Comp in 9mm is the perfect addition to your 1/2x28 threaded 9mm pistol. The quad port design reduces muzzle flip and felt recoil and gets you back on target fast for shorter split times and improved battlefield effectiveness.  The mil spec hardcoat anodized matte black finish protects the CNC machined 7075 T6 compensator from wear and reduces the visual footprint.   Easy access 6-32 set screws make timing your compensator quick and easy. Recommended that you use high heat lock tight on all threads.    Tech Specs Material: 7075 T6 Finish: Mil Spec Hardcoat Anodized Matte Black Thread Size: 1/2x28 Caliber: 9mm Luger Weight: .86oz Length: 1.34"   General Compensator FAQ Compensators function by redirecting exhaust gas up and to the sides, this means there is less felt recoil energy for the shooter and less muzzle flip. Because their is less recoil energy with a compensator you may need to use a lighter recoil spring for your gun to cycle correctly. In most cases the mid comp will cycle with a stock spring with 124gr and heavier ammo, however lighter loads and certain combinations of slides/optics/barrels may require you lower your recoil spring weight. If you experience FTE or FTF after attaching a compensator this usually means you need a lower lbs recoil spring.  Firearms in images are shown for illustrative purposes only, they are not included with the compensator.