The 1911 MagWell Mainspring Housing is a grip part made by Fusion Firearms, designed for various gun makes such as Colt, Kimber, Ruger, Sig, and Springfield. It is suitable for handguns in .45 ACP, 9mm, 40 S&W, and 10mm calibers. The mainspring housing is low profile and made of stainless steel with a silver color finish, providing a sleek and durable upgrade for your 1911 model.