Counter sink drill bits sink holes into most machinable metals, plywood, softwood, hardwood, fiberglass plastic, mild steel.Metal countersink bits are made from industrial grade high-speed steel for increased durability.Each sink has a black oxide coating to resist corrosion.90 degree countersink a five-flute design removes chips faster and dills smoother and ensures an extended life.Head diameter: 12mm, 16mm, 19mm(1 inch=25.4mm)Steel countersink bits 90-degree tip drills can drill holes on almost any material, with unique design, high efficiency, convenience and speed.Material: carbon steelcolour: silverPackage Contents: 3 x 12/16/19mm Drill BitOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.