FightLite Raptor Belt-Fed AR-15 5.56x45mm NATO 16.25inch Upper Receiver M-LOK Rail 1-7 Twist 1/2x28 Anodized Black. Once installed" the patented RAPTOR upper receiver system allows you to feed from standard box type AR15/M16 magazines or M27 linked ammunition. Spanning the capability range from the optic ready carbine through a lightweight support rifle. The RAPTOR can be user-configured in seconds without tools to adapt to virtually any mission profile. Utilize their Dual-Feed(R) technology at operator discretion" permitting unprecedented firepower and weapon flexibility. Specifications for FightLite Raptor Belt-Fed Upper AR-15 5.56 x 45mm NATO 16.25 inch Upper Receiver: Manufacturer: FightLite Caliber: 5.56x45mm NATO Barrel Length: 16.25 in Finish: Black Color: Black Handle Color: Black Features of FightLite Raptor Belt-Fed Upper Complete Upper Receiver 556NATO 16.25 Threaded Barrel MLOK Rail Fits AR-15 Lower Reciever Anodized Finish Black: Accepts M27 Linked Ammunition Package Contents: FightLite Raptor Belt-Fed Upper Complete Upper Receiver 556NATO 16.25 Threaded Barrel MLOK Rail Fits AR-15 Lower Reciever Anodized Finish Black FightLite RPTR-001: Raptor Belt-Fed AR-15 5.56x45mm NATO 16.25inch Upper Receiver M-LOK Rail 1-7 Twist 1/2x28 Anodized Black