This Matador Arms MAT-916 Roller Delayed Bufferless Upper Receiver Assembly is side-folding compatible and features Matador Arms patent-pending EZTS "Easy Take-down System" with no tools required to break down the upper for maintenance and cleaning. The Extended Rail System (ERS) is included and pre-installed on this upper receiver, to extend the handguard over the 16" barrel. 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 ERS is M-LOK compatible throughout to extend the accessorization of the upper receiver with lights, lasers, optics, etc.The MAT-916 9mm AR upper is compatible with AR-9 Lower receivers in any double-stack magazine configuration:GlockSig SauerColt Stick MagazinesHK MP5CZ Evo Scorpion FeaturesNon-reciprocating steel charging handle (ambidexterous)4140 Nitrided...