PRECISION REFLEX, INC MK12 MOD-H .223/5.56 NATO COMPLETE UPPER RECEIVER FOR AR-15 TheMK12 Mod H upper is 16.5" barreled upper with capable MOA accuracy. The flat top receiver has a Gas BusterA(R) charging handle with military big latch, Pri rifle length black finished forearm, recce top rail that connects to the forearm rail. The upper also comes with a bolt carrier group, PRi's rail mounted flip up front and rear sights and AE brake and collar. The upper is designed to have two levels of top rails for mounting of night vision in front of scopes. All uppers are assembled cleaned and tested before shipping. Please allow 5~10 days for assembly and te Mfg: Precision Reflex, Inc.