The serrations on this mainspring housing help get the weight in the right place and gives you good traction. Pins and springs do not come with this part. You can use the pins and springs from your original mainspring housing or purchase new parts from us. This mainspring housing makes a great replacement for plastic mainspring housings. This is our premium mainspring housing, designed and made by EGW. Fully machined from bar stock. This item will fit 1911 Government and Commander frames, it will not fit STI's or short grip frames. Our G.I. Arched Mainspring Housing is machined from carbon steel barstock. Lanyard loop and pin are supplied. Mfg: Egw
