Step Spiral Groove Cone Drill TiN Coated/HSS-Co Cobalt Bit Set Hole Metal Cutter. Material: HSS (Titanium HSS / HSS Cobalt). Size :4-12mm (Level 5), 4-12mm (Level 9), 4-20mm (Level 9), 4-32mm (Level 15). Notification :Water is required for lubrication when drilling, which can extend the life of the drill bit. Titanium HSS :Suitable for materials with hardness below 23°, such as aluminum, PV board, plastic, wood board, ordinary iron with thickness within 2mm, etc. HSS Cobalt :Suitable for materials with high hardness, such as steel plate, aluminum plate, carbon steel, stainless steel sheet, etc. The thickness of stainless steel plate below 1mm and iron plate aluminum below 5mm. Specially designed for precision drilling of holes in aluminium, brass, copper, plastic, steel and wood. Manufactured from high steel for increased durability and cutting power. Titanium coated to reduce friction and heat. Each step is clearly labeled with the depth diameter in steps. 118° X-shaped opening design in order to prevent slippage when in chuck. Package Include : According to your choose. We care about our valued buyers, if you have any questions, our Customer Service staff will be very glad to help you. We try our best to reply to your emails as soon as possible, however, due to the high volume of daily incoming emails and time zone difference, we may not be able to reply to your emails immediately. For the functional products in our shop, we make sure that the functions are the same as the description, but the actual color and shape may look a little different from the pictures because of the technical improvement and manufacturing variance.