Irwin Tools 1853536 Multi Material Set (5-Piece) Durable carbide tipped construction Brazed carbide tip has a unique diamond ground 4-face design for excellent centered starts with little walking and best hole quality Double ground flute ensures fast and efficient removal of the drilling dust and prevents clogging Special duo tone surface finish reduces friction and resistance, increasing bit life and drill battery life Special Grind Angle creates sharper tip edges for Fast starts in tough materials