Diamond coated drill bits and rotary bits for power tools. These bits all have a 1/4" diameter shank for medium speed power tools. These tools are machined from high quality carbon steel, then coated with diamonds using a proprietary multi-layering process. This means faster, smoother cutting and less heat buildup. Maximum RPM is 5,000 or less. These diamond bits are used in a variety of household and commercial uses including drilling, cutting and shaping, glass or ceramic tile. The 1/4" shank is most commonly used in power drills and routers.