Only the finest polymers or high carbon heat-treated steel go into our magazine bodies. ProMag magazine bodies are constructed of high carbon heat-treated steel and TIG-welded for strength. The springs are precision wound using heat-treated chrome silicon wire. Bases and followers are injection molded from polymers selected for their durability. This produces the finest quality magazines that perform under the harshest conditions.Gun MFG: ColtGun/Pistol Type: Govt. 45 ACP Caliber:Material: SteelCapacity: 15 RoundColor: Blue