The UDP-9 SBR is a compact lightweight 9mm AR-15 short barrel rifle. It accepts any 9mm double stack GLOCK� magazine and features last round bolt hold open. All NFA rules apply. - Last round bolt hold open on an empty magazine - Flared magwell for faster reloads - Integrated oversized trigger guard - 7075-T6 billet aluminum lower with a matte black hard-coat anodized finish - 7075-T6 billet aluminum slick side upper receiver with appropriately sized ejection port and no forward assist or dust cover - Threaded bolt catch screw - 9mm bolt assembly for use with a standard AR-15 hammer - 6� 9mm barrel in chrome moly with a 1/10 twist black melonite finish and A2 style flash suppressor - Barrel is threaded 1/2�36 and can accept a suppressor - Magpul MOE stock and Magpul K2 pistol grip - Angstadt Arms 5.5� free float M-LOK hand guard with a modern ergonomic 7 side design that allows for 45 degree offset mounting options - Continuous top mil-spec 1913 picatinny rail - Weight: Sub 5lbs - Length: 24 - Patent pending - Accepts all Glock� aftermarket magazines. We recommend using factory Glock� magazines - Includes one 15 round Glock magazine