The 0940 is a dedicated GLOCK magazine fed AR-15 lower receiver set configurable in 9mm, .40 S&W and .357 SIG. It features last round bolt hold open. Last round bolt hold open on an empty magazine (LRBHO) Flared magwell for faster reloads Accepts 9mm, .40 S&W and .357 SIG GLOCK(R) magazines Integrated, oversized trigger guard Machined from 7075-T6 billet aluminum with a matte black hard-coat anodized finish Works with any mil-spec upper receiver Threaded bolt catch screw For use with a 9mm bolt carrier assembly and a standard AR-15 hammer Lower weight: 10 oz Patent pending Accepts all aftermarket Glock(R) 9mm double stack magazines. We recommend using factory Glock(R) magazines