The YHM lowers are machined 100% in house from forged 7075-T6 aircraft grade aluminum. They feature over sized magazine well chambers for easier magazine changes. They will accept all generations of PMAG's and mil-spec upper receivers. They fit all standard parts and are finished in hardcoat anodized matte black to military specifications or better. NOTE: Requires a lower parts kit, buffer & stock of your choosing to complete.