Convert your standard AR-15/M16 lower receiver (not included) into a Colt® 9mm SMG receiver with the ProMag® AR-15/M16 9mm Magazine Quick Change Adapter Block – Black Polymer. Constructed of high strength polymer with steel hardware, this magwell adapter block offers easy installation, readily accepting 9mm Colt SMG-type magazines for field-ready performance. Plus, this all-in-one adapter features a steel roller, ejector, and bolt stop for reliable performance and lasting durability. For use with 9mm upper receivers only (not included).