Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Reciever 4150 Lightweight Nitrided Barrel 1-10 Twist 1/2x28 Threads Anodized FDE. The 9mm upper is machined for maximum weight reduction slim profile and compatibility with bolt catches and lower receivers. The upper is also built with a tapered multi-material 4-piece trunnion system to maintain mechanical accuracy and durability. The MAT-9 9mm AR upper is compatible with AR-9 Lower receivers in any double-stack magazine configuration: Glock Sig Sauer Colt Stick Magazines HK MP5 CZ Evo Scorpion. With an AR-15 Lower Receiver it requires Matador Arms Mag-X magazine conversion kit or equivalent type product such as Endomag. The Roller Delayed system designed for our MAT-916 upper reduces recoil lightens the upper and increases reliablilty. The lack of a need for buffer tubes increases agility and protability in compact spaces. The flexibility of the non-reciprocating and reversible charging handle makes the MAT-9 the perfect platform for any shooter. Specifications for Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Receiver: Manufacturer: Matador Arms Caliber: 9mm Luger Barrel Length: 16 in Barrel Profile: Tactical Lightweight Barrel Twist Rate: 1-10 Threads per Inch: 1/2x28 Muzzle Device: Thread Protector Finish: Anodized Fabric/Material: 6061-T6 Aluminum Handguard Length: 23 in Gun Rail: M-LOK Gun Make: AR Platform Gun Model: AR-9 Barrel Material: 4150 CMV Steel Features of Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Receiver Non-reciprocating steel charging handle (ambidexterous) 4140 Nitrided steel bolt and action parts 6061-T6 anodized upper receiver 4150 Lightweight Nitrided Barrel 16in long 1:10 twist 1/2x28 threads NATO 1913 Spec top rail Compatible with LRBHO (Last Round Bolt Hold Open) lower receiver Ready to run with a Suppressor right out of the box Extended Rail System The Extended Rail System (ERS) extends the hand guard beyond the Upper Receiver to protect your hand from barrel heat. With added length for improved handling you can easily attach a variety of accessories including lights lasers and optics to customize your setup for any mission. M-LOK compatible system throughout. Package Contents: Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Receiver What firearm models does the manufacturer say Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Receiver is compatible with? The manufacturer suggests that Matador Arms MAT-916 AR-9 9mm 16in Roller Delayed Upper Receiver is compatible with AR-9Matador Arms MATK-U-16-FDEOP: MAT-916 AR-9 9mm 16in Roller Delayed Upper Reciever 4150 Lightweight Nitrided Barrel 1-10 Twist 1/2x28 Threads FDE