We kept looking until we finally found these premium quality, smooth cutting stones to give you the ultimate combination of hardness, cutting speed and finish for shaping the ejection port roll-over notch on those tough, 1911 Auto slides. Start with the B51 stone for either the short or long style notch, then finish up with the B42 to bring the long style notch to full depth. Cobalt impregnated aluminum oxide stones cut fast but will not gouge or tear the metal. You get a smooth, ready-to-finish surface that can be polished or bead-blasted. Stones can be reground and reshaped so they last through job after job. Hardened steel shanks are nickel-plated for long life and sta Mfg: Brownells SPECS: Cobalt impregnated aluminum oxide, 120 grit. Includes (2) B51, (2) B42 stones and instructions. 1/8" (3mm) dia. shank.