ProMag PM237B Magazine Quick Change Adapter Block made of Polymer with Black Finish for 9mm Mags to fit AR-15 Lower Receiver
Made in the USA, this Quick Change Adapter Block adaptor block easily installs in AR-15/M16 lower receivers to allow the use of 9mm Colt/SMG type magazines with 9mm upper receivers. The block is constructed of high strength polymer with steel hardware, roller, ejector, and bolt stop. Allows quick install without the need to remove the bolt stop roll pin.