Fusion Professional Series Aluminum alloy Light weight Mainspring Housing, Standard Government size. So this will fit all 1911 pistols full size, commander and Clones. CNC Machined from aluminum alloy bar-Stock, With 25 lpi Checkered back. Clear anodized to resist corrosion. All CNC machined in the USA,. No MiM, No Cast, ALL Solid CNC Machined Bar-Stock. You will not find better quality for your money…