This 5-Piece Titanium coated countersink set from Mibro - a 60 plus year old company selected as one of Canada's "50 Best Managed Companies" contains sizes 1/4-Inch, 3/8-Inch, 1/2-Inch, 5/8-Inch, and 3/4-Inch. Ground from special alloy steel with hardened edges and coated with Titanium to extend service life up to 6 times that of uncoated products. They will cut quickly and easily in soft metal, wood, rubber, plastic and other machinable materials. The Counter sink is used to drill a conical depression to allow screw heads to be flush or recessed from the surface of the material. It also is excellent in removing the burr from newly drill holes to improve the appearance and remove sharp edges.