The blade is made of high-quality alloy, which is very and resistant to cutting. Has good sprinting ability. The effective length is 20mm, which can process thick steel plates and thick-walled metal pipes. When cutting coolant, the must be filled with coolant. It can be clamped on electric drills and bench drills, and can be used to drill thick steel plates, cast iron, stainless steel, non-standard angle iron and other metals. Total length: about 65mm Shank diameter: about 9mm Material:alloy colour:Silver Package Contents: 12 x drill(15/16/18/20/21/22/25/26/28/30/35/50) mm Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.