Heckler & Koch Steel Pistol Magazine USP9 Expert 9mm Luger 18 Round Black 18. It is constructed of steel with a polymer coating. Specifications for Heckler & Koch USP9 Expert 9mm Luger 18 Round Steel Pistol Magazine: Manufacturer: Heckler & Koch Gun Make: Heckler & Koch Gun Model: Heckler & Koch USP 9mm Luger Caliber: 9mm Luger Magazine Capacity: 18 Round Color: Black Quantity: 1 Fabric/Material: Polymer Number of Rounds: 18 Package Contents: Heckler & Koch USP9 Expert 9mm Luger 18 Round Steel Pistol Magazine What firearm models does the manufacturer say Heckler & Koch USP9 Expert 9mm Luger 18 Round Steel Pistol Magazine is compatible with? The manufacturer suggests that Heckler & Koch USP9 Expert 9mm Luger 18 Round Steel Pistol Magazine is compatible with Heckler & Koch USP 9mm LugerHeckler & Koch 50259081: Steel Pistol Magazine USP9 Expert 9mm Luger 18 Round Black 18