The UDP-9 rifle is a lightweight 9mm AR-15 rifle and accepts 9mm double stack Glock magazines. It features last round bolt hold open; flared magwell; oversized trigger guard; no forward assist or dust cover; threaded bolt catch screw; 9mm bolt assembly for use with a standard AR-15 hammer; Mil-Spec AR-15/M4 Fire control group; 5.50″ free float ultra light M-LOK handguard and Mil-Spec 1913 Picatinny rail. The UDP-9 is compatible with most aftermarket 9mm PCC triggers. Accepts all Glock aftermarket magazines. We recommend using factory Glock magazines. Includes one 15rd magazine.