Ed Brown mainspring housings are fully machined from solid bar stock steel. No cheap castings or plastic is used. We offer a variety of treatments, including smooth, serrated, checkered, , Snakeskin, Chainlink I, and Chainlink III. The Government Model housing features drop-in installation in all full-size 1911 pistols including full size Para-Ordnance pistols such as the P-14 and P-16. All housings will work great with any finish or type of steel, including aluminum. Internals not included, may be purchased separately.