Diameter: 1/4 inch, Overall length: 2-5/8 inch, 1/4-inch shank (6mm diamond drill bit) Shank: 1/4" hex shank. These 1/4" diamond drill bits are part of the Quick Change universal hole saw system, which lets you change hole saws in seconds. MUST USE WITH WATER throughout the process. Recommended using at a low speed and low pressure.For cool cutting lubricate with water for extended life. Wide application: 1/4 inch diamond hole saw drill holes in glass bottles,hard tile,porcelain,ceramic plant pots,granite,marble slab and stones. DaduoRi 1/4 inch Diamond Drill Bits with Quick Change Shank for Glass Granite Porcelain Tile Ceramic Marble Stone, 1/4" Tile Drill Bits x 2 Pack