Fusion Firearms Mag-well Mainspring Housing Gov Checkered Black. 2 piece Dovetail base well with set screw. This is a Pro-Series Chain-link pattern mainspring housing. All Machined from Stainless steel bar stock and great looking and feeling cut chain-link pattern. These are as nice as they get. Specifications for Fusion Firearms 1911 Mag-well Mainspring Housing: Manufacturer: Fusion Firearms Fabric/Material: Carbon Steel Gun Make: 1911 Platform Condition: New Package Contents: Fusion Firearms 1911 Mag-well Mainspring Housing What firearm models does the manufacturer say Fusion Firearms 1911 Mag-well Mainspring Housing is compatible with? The manufacturer suggests that Fusion Firearms 1911 Mag-well Mainspring Housing is compatible with Colt 1911 Government 5in Colt 1911 OfficerFusion Firearms 1911-MSH-27-3: 1911 Mag-well Mainspring Housing Gov Checkered Black