The Hogue Aluminum Mainspring Housing is precision machined from solid billet stock Aerospace grade 6061 T6 aluminum. Carefully engineered and sized for ultimate fit, form and function, the Hogue Aluminum Mainspring Housing is perfect for dressing up or customizing your prized 1911. Hogue Mainspring Housings are available with a smooth finish or with precision sharp, crisp checkering; flame, brushed or matte finish and an arched or flat profile. They also feature a hard Type III anodized finish available in a variety of colors.