Concrete drill bits featuring diamond ground percussion carbide tips, and optimised 2-flute, ground and sharpened cutting edges for fast, smooth cutting. Custom-engineered steel construction with black oxide coating for prolonged life. Ideal for drilling in brick, tile, ceramic, concrete, plaster, slate and aerated concrete blocks. Also features 3-flat, secure grip shank to prevent the drill bits slipping in the chuck whilst ensuring maximum transmission of torque, and laser-engraved size markings for best long term visibility. Optimised for use with high speed cordless drills. High-Speed Steel Straight Shank 4mm-10mm Dia. Drill Bits Suitable for Brick, Tile, Ceramic, Concrete, Plaster, Slate & Aerated Concrete Blocks Carbide Tip For 1/2" Chucks - Use with Pilot Drill High-Speed Steel Straight Shank 4mm-10mm Dia. Drill Bits Suitable for Brick, Tile, Ceramic, Concrete, Plaster, Slate & Aerated Concrete Blocks Carbide Tip For 1/2" Chucks - Use with Pilot Drill