Features:<br /><br />    Brand new and high quality. <br />    High Speed Steel， Titanium Nitride Coated. <br />    1/4¡± Hex shank for quick chang and sure grip. <br />    Tri-flat shank for sure grip. <br />    Self-starting tips will not skid ， no need for center punching or pilot drill. <br />    Color: Golden. Material: High speed steel. <br />    Include Sizes:<br />    1: 4mm to 12mm 9 Steps (4mm， 5mm， 6mm， 7mm， 8mm， 9mm， 10mm， 11mm， 12mm)， 7cm(L). <br />    2: 4mm to 20mm 9 Steps (4mm， 6mm， 8mm， 10mm， 12mm， 14mm， 16mm， 18mm， 20mm)， 7cm(L). <br />    3: 4mm to 32mm 15 Step(4mm， 6mm， 8mm， 10mm， 12mm， 14mm， 16mm， 18mm， 20mm， 22mm， 24mm， 26mm， 28mm， 30mm， 32mm)， 10cm(L). <br />    Note:<br />    When drill the hardness and larger diameter hole， must cooling the bit with cool water， recommend the drilling rate for 120-240 is suitable for processing 6mm and below plate， the bits are high speed steel material， drilling rate are 120/minute， expanding to more than 20 mm hole， drilling rate shall not be higher than 400 RPM and used water cooling.<br /><br />Package Included:<br />    3 x Spiral Grooved Step Drills<br /><br />NO Retail Box. Packed Safely in Bubble Bag.