The Angstadt Arms bolt carrier group is compatible with GLOCK magazine AR-15 builds. The 9mm version is also compatible with Colt style magazines. Add an Angstadt Arms dedicated pistol caliber buffer kit for the best possible performance. FeaturesMachined from 8620 alloy steel with a QPQ black nitride finishCompatible with GLOCK magazinesFor use with a standard AR-15 hammerIncludes removable weight for use with Law Tactical folding stock adapter