The Extreme Service Hammer Strut is correctly designed for all 1911 applications. The shape of the hammer strut is designed to prevent the hammer strut from rubbing the sear spring, which can cause the tension of the sear spring to unload. The Extreme Service strut is wire EDM machined from hardened tool steel for maximum durability and high strength, giving the reliability you can count on from your 1911. Available in the white or in IonBond Black DLC. Mfg: Harrison Design & Consulting Tool steel construction. Available unfinished or with IonBond Black DLC coating.