Item Type: Twist Drill Bit Material: High Speed Steel Application: Hand drill, bench drill processing equipment, etc. Function: For drilling stainless steel, drilling copper, drilling iron, drilling aluminium alloy and other steel materials. Drill Bit Size(Approx.)Total Length(Approx.)Working Length(Approx.) 10.0mm / 0.4in133mm / 5.2in92mm / 3.6in 10.5mm / 0.4in133mm / 5.2in92mm / 3.6in 11.0mm / 0.4in142mm / 5.6in99mm / 3.9in 11.5mm / 0.5in142mm / 5.6in99mm / 3.9in 12.0mm / 0.5in151mm / 5.9in106mm / 4.2in 12.5mm / 0.5in151mm / 5.9in106mm / 4.2in 13.0mm / 0.5in151mm / 5.9in106mm / 4.2in Package List 5 x Twist Drill Bit 1Suitable for electric drill and bench drill, etc., also suits for drilling stainless steel, copper plate, iron plate, aluminium alloy and other steel materials. 2The drill bit is accurately made of Tiplated highspeed steel, with high hardness and good heat resistance. 3The cutting edge has high strength for fast gouging speed, which will effectively improve work efficiency. 4The Sshaped spiral groove of the drill bit is beneficial to lead out the shavings and save time and effort. 5A powerful grinding wheel makes the blade groove sharper, and makes the driller sturdy and durable.