Gryphon 1 1/2 Inch Core Drill Bit "Hole Saw" Diamond Coated 40mm Great for drilling holes in slumped lamp shades Use: Drill holes in glass Bit: 1-1/2" outside diameter, 30mm shank length, 12mm shank diam. Features: - Cuts holes in glass quickly & easily - Use with drill press - Spray diamonds with water to keep cool while drilling - Use press-release-press-release action to minimize heat & allow coolant to flush away debris