This is our shortest and lightest HALO to date. The closer mechanism is improved for use on the standard A2 birdcage style flash hider blank firing adapter groove. It is also compatible with the Primary Weapon Systems KAC556 mount.SpecificationsCaliber5.56mmSound Tested134dB Colt(R) M4 Carbine 5.56 14.5"Diameter1.5"Overall Length6.9"Weight12.2 oz.Mount Type5.56x45 Universal, Fits A1/A2 Flash HiderTube MaterialTitaniumFull Auto RatedYesTube FinishBlack High-Temperature Cerakote(R)