The MONTGO-9 blowback 9mm AR upper receiver, with NO BUFFER! Compatible with any AR-15* and/or AR-9 lower, the Montgo-9 gives shooters endless build possibilities while being compact and versatile. Solid end receiver...does not require a buffer / Hard anodized billet aluminum / 5.5" barrel, 4140 Nitrided / ?x28" threaded barrel / Full length integral picatinny rail for installing optics or sights 3.5" bottom picatinny accessory rail / Non-reciprocating charging handle...can be used on right or left side / 4140 steel nitrided bolt & trunnion for durability / No tools required for field stripping / OAL: 12.125", Width: 1.47", Weight: 3.5lbs / *AR-15 lowers w Mfg: Matador Arms