This is a Fusion Firearms Pro-Series 1911 colt style Precision Pro Series, Serrated Slide stop in heat treated alloy carbon steel with black protective finish. For 9mm/38 Super Caliber pistols Precision machined from Bar Stock. This is a very high quality part, No-MIM. .1995 - .2005" diameter shaft to help aid in precision lock-up. Great product for new build 1911's and rebuild projects.