Challis hex drive bushings are a breakthrough design, perfect for a custom build, replacing damaged bushings. Uses a 7/32" nut driver which allows you to feel thread engagement and avoid damaging cross threading, and the robust hex head will handle the torque needed for proper seating, without concern for distorting the bushing or slipping and scratching your gun. Using the same driver, they are easily removed with no risk to frame or bushing. Unlike the old style, Challis bushings can be reused multiple times. Hex drive bushings can be fit with an optional O-ring which keeps grips snugly in place and minimizes shock to the grips and bushings during discharge. Use of O-rings wil Mfg: Challis Grips SPECS: For grips not less than 0.24" thick.