Machined from 7075 T-6 aluminum with a matte black anodization finish, this 80% lower receiver from Matrix Arms is the ultimate foundation for your next AR-15 rifle or pistol build chambered in .223 Rem / 5.56x45mm. Both "FIRE" and "SAFE" are engraved on the sides while the rest of the 80% lower unit is blank. Simply put in the last 20% of work and