Gemtech THREAD PROTECTOR-M13.5X1 LH 12223

Gemtech Thread Protector (M13.5x1mm LH) Caliber Sound Reduction Diameter Length Weight Mount Material Full Auto Rated Finish For Sig P226, HK USP9SD, and Smith & Wesson M&P9 SpecOp. These protectors will tighten down easily onto most any appropriately-threaded pistol or rifle barrel, keeping fine threads from being damaged from bumping around gun cases, or when you're not using your suppressor.