A short and extremely durable suppressor the HX-QD 556k updated with our newly designed flash cap is built with patented and proven OSS Flow-Through technology delivers sub-140 dB and zero flash performance is full-auto rated easily passes the USSOCOM Reliability Stress Test and has no minimum barrel restrictions it's designed and built for extreme use. - Compatible with Muzzle Brake-QD 556 and Flash Hider-QD 556. - WEIGHT 15.3 oz - LENGTH 5.9 in - DIAMETER 1.62 in - Materials & Finish: Unlike traditional suppressors that manage trapped gas intense heat and pressure with blast baffles OSS Flow-Through technology redirects expanding gases forward allowing us to use 17-4 stainless steel deflectors and internal Grade 5 Titanium coils. The result is a remarkably cooler and extremely durable suppressor. The HX-QD 556k has a fully-welded outer body made of 17-4 heat treated stainless steel coated with C-series high temperature black Cerakote. - Sound Pressure Levels: The HX-QD 556k was designed with minimal length in mind. The low volume and light weight make this suppressor ideal for shooters more concerned with size than maximum sound reduction. Sound pressure levels are measured at the shooters ear to comply with current military specifications: - 136-140 dB on 20 AR15 DI using commercial grade 55 gr ammo - 138-142 dB on 16 AR15 DI using commercial grade 55 gr ammo - 142-146 dB on 10.5 AR15 DI using commercial grade 55 gr ammo