Highly recommended for both heavy recoiling 1911s and also 1911s with shorter than Gov't Model slides. The Extreme Service firing pin stop is CNC machined out of an oil-quenching tool steel that was chosen for a balance of impact and wear resistance, with a GI hardness is 44-50Rc. The Extreme Service FPS is made .482" wide so it can be fitted to your slide and extractor to prevent extractor "clocking". It has chamfered fitting pads on each side to make your job easier and the FPS fit better into the slide. It has a 3/64" radius machined on the bottom rear corner and a 3 degree angle at the top rear face, both of which act to take away mechanical advantage from the Mfg: Harrison Design & Consulting