Evolution Gun Works 1911 Premium Mainspring Housing/Magwell Combo Blue. The mainspring housing provides a base to build upon with additional machining enhancements. The magwell enhances the magazine release and beefs up the end of the housing allowing it to be seated completely into the frame with no work on your part. The magwell along with the mainspring housing give your 1911 a polished all steel look. The two-piece magwell was designed with a rounded bottom to clear the hammer and accommodate the ejection port of most 1911 model magazines. Machined from solid steel bar stock and dualnitride finished. This ensures a durable blemish free finish. Specifications for Evolution Gun Works 1911 Premium Mainspring Housing/Magwell Combo: Manufacturer: Evolution Gun Works Fabric/Material: Steel Design/Pattern: Checkered Gun Make: 1911 Platform Gun Model: 1911 Condition: New Package Contents: Evolution Gun Works 1911 Prem. Mainspring Housing/Magwell Combo What firearm models does the manufacturer say Evolution Gun Works 1911 Premium Mainspring Housing/Magwell Combo is compatible with? The manufacturer suggests that Evolution Gun Works 1911 Premium Mainspring Housing/Magwell Combo is compatible with 1911Evolution Gun Works 11421: 1911 Premium Mainspring Housing/Magwell Combo Blue