Features:<br />100% brand new and high quality<br />Unique ladder structure ， it can open multiple Aperture<br />it can not easily be broken.<br />It can deburr， chamfer and open hole， but ordinary twist drill can't<br />Little rock， it can carve out a nice aperture without firstly using a center punch<br />Tool using: pistol drill， bench drill. Water to make ti cool while working， it can effectively extend the service life.<br />Recommended drilling speed 250--400 rpm<br />Suit for use in hardness under 25° artifacts，The plate thickness under 5mm<br /><br />Specifications:<br />6-60mm(12 steps:6，10，15，20，25，30，35，40，45，50，55，60mm)<br />Shank Diameter: 13mm<br />Material: HSS 4241<br /><br />Package Included:<br />1pcs HSS 4241 Spiral groove step drill