American Tactical Imports is producing this no nonsense AR-15 durable aluminum lower receiver. This receiver is crafted from precision machined aluminum with multi caliber markings and ready for your next high performance AR platform build. It's ready to accept any standard AR-15 upper assembly for fantastic fit and function. This is a multi-caliber lower that can be used with any standard AR caliber build including .22 LR 5.56 NATO .223 Rem .300 BLK or 6.8 SPC. If you're looking for an affordable solid AR lower to start your next build then you're looking for the ATI Milsport Stripped Lower Receiver!