MR556 Match Rifle 5.56mm 16.5 Inch Barrel Black Finish KeyMod Handguard Troy Folding Sights Adjustable Polymer Stock 10 Round. Gas operated system. Two stage trigger. Five-position adjustable stock. Cold hammer forged 16.5 inch barrel with a 1:7 inch right hand twist rate. Ergonomic pistol grip; Troy folding BattleSights. Free floating KeyMod compatible handguard system with full length top rail. Additional rail sections at 3 and 9 o-clock for adding accessories. Flash hider. Metal magazine. Includes Allen tools, gunlock and instruction manual. Ships in a soft-side, padded tactical gun case with H&K logo, outside pockets, MOLLE attachments.