Taper length drills and taper shank drills have the same flute length. Straight-shank drills feature cylindrical shanks that are the same or different diameter as the drill body. They are available with cutting angles of 90 degrees, 45 degrees, or less than 45 degrees. All twist drill sizes have a common center-to-center distance between their threads: 16mm, 12mm, 9mm, and 7/8th inch (12mm, 10mm, 8mm, and 6mm). Drills can also be made from metal alloys for use in specific applications at smaller diameters. For example, carbide-tipped drills are used in fine woodworking and metalworking to cut without marring the surface being drilled. The term "size" of a twist drill refers to its external thread diameter. Size may also refer to the diameter of the shank, where a larger size means more material is removed when drilling holes in wood. The actual depth of a hole depends on two factors: the height of the drill bit above the workpiece and the rotational speed of the drill. At low speeds, bits will usually touch bottom before they reach the desired depth; at high speeds, the hole will be drilled deeper before it slows down.