MORTAR REMOVAL - Ideal for intricate and delicate mortar removal where a diamond blade wouldn’t fit or be too difficult to use. VACUUM BRAZED - Made with premium super-abrasive vacuum brazed diamond, this bit will grind faster, last longer and cost you less than any comparable tool. SPECIFICATIONS - 4-5/8" long X 1/4" shank fits on most drills. Use on a regular drill. Do not use a impact drill. Allow the bit to do the work, do not apply too much pressure, and allow bit to cool down during use to prevent bending or breaking. LIFETIME WARRANTY - All Delta Diamond Products, Inc Diamond Blades, Coring Bits, Hole Saws and Grinding Wheels include a lifetime warranty against warping, cracking, and material defects. If any diamond tool (being used under its intended use with at least 50% wear left) fails to cut or work properly, or if the bond between the diamond segment and the steel core becomes separated at any time, the diamond tool will be replaced. Make sure the shank is straight and smooth when installing. Use with variable speed die grinders and drills. Begin at a low RPM with each use. Maximum safe operating speed is 6,000 RPM. Do not use at an RPM where the bit vibrates or wobbles. Do not push, twist, bend or apply pressure to the tip of the bit.