I have bought 3 of these so far and used the Harrison Design True Radius Sear Jig on each one, now I know that the trigger and trigger pull weight doesn't just rest on the sear and shape of the sear but when all is said and done, gun and other parts have been polished to perfection, and the sear spring has been tuned to my liking these sears and the True Radius Sear Jig can't be beat. I have and have used a bunch of sears in my own personal quest for the best 1911/2011 parts: Wilson Combat Bulletproof, Nighthawk, EGW, Infinity, Cylinder and Slide, Fusion, Nowlin, and even Extreme Engineering (basically C&S copy for less $) and these gunsmith sears are my favorite. I don't know what kind of tool steel they are made of, lots of makers will try and advertise a specific tool steel to sell a product or whatever but I don't think it matters much as long as it's been properly heat treated and these definitely are and my go to sears for running through my True Radius Jig, they will probably last the life of the gun and longer. Not far behind these are the C&S sears and EGW, but the Harrison Design sears are the best IMHO.