This countersink drill bit set is made of , which can withstand use. Features the high-speed steel, aluminum alloy and sponge material, which has high durability, not easy to deform. Fine workmanship, ensures practicality. Features -Color:Assorted Color -Material:High-speed steel, aluminum alloy, sponge -Size:5.70X1.90X1.90cm,5.70X1.50X1.50cm,5.70X1.20X1.20cm,5.70X0.95X0.95cm,5.70X0.63X0.63cm/2.24X0.75X0.75in,2.24X0.59X0.59in,2.24X0.47X0.47in,2.24X0.37X0.37in,2.24X0.25X0.25in - It is not easy to be stuck in loading and unloading, it is more convenient to use, and it is not easy to slip and more firmly in use. - Made of high speed steel with an oxidized gold finish for corrosion resistance. - The five design reduces vibration for smoother drilling and longer bit life. - Precision ground 82-degree tip drills holes in most machinable metals as well as wood and plastics. - Counterbore and chamfering operations can be performed on wood, aluminum and iron parts. Package list: 1 x 3/4 inch countersink drill bit 1 x 5/8 inch countersink drill bit 1 x 1/2 inch countersink drill bit 1 x 3/8 inch countersink drill bit 1 x 1/4 inch countersink drill bit