DESIGN- Each drill bit has a double end and is ground with a standard 60 degree included angle.FIT- Used for producing center supports in components or work pieces requiring machining between centers.MATERIAL- Material: HSS, Applicable hardness: HRC40 or less.SIZE- The set includes 5 sizes: 1.5mm tip diameter with 5mm body diameter and 35mm length & 2.0mm tip diameter with 5mm body diameter and 41mm length & 2.5mm tip diameter with 6mm body diameter and 45mm length & 3mm tip diameter with 8mm body diameter and 51mm length & 4mm tip diameter with 10mm body diameter and 60mm length.Features:These drill bits Center drills are used in metalworking to provide a starting hole for a larger drill bit. They can also be used to make a tapered indentation at the end of a workpiece to mount a lathe center. Made of high speed steel, these center drills are of high hardness and good wear resistance. There are 5 pieces center bits in this set which can be used to drill holes in different sizes. Widely used on lathe machines, these center drills can cut easily and remove chips smoothly. Usage: Spotting and spotting drills are traditionally used to form a tapered hole for a lathe center to provide a starting point for a standard twist drill. Designed to prevent the drill from walking. Used for producing center supports in components or workpieces requiring machining between centers. Note