This Magazine Well Insert Assembly is designed to work exclusively with the Ruger Pistol Caliber Carbine. It accepts all Glock-style 9mm magazines as well as SR9, and Security-9 9mm magazines. The flush-fit design is made from rugged, glass-filled polymer material for strength and durability. Quick and easy installation; instructions included with this product. The 5/32" hex wrench included with Pistol Caliber Carbine is required for installation.