The BlueSpot Tools HSS 1/4in Hex Shank Step Drill is ideal for precision drilling in aluminium, brass, copper, plastic, steel and wood. Drills holes in 2mm increments from 4 - 22mm. Manufactured from high speed steel for increased durability and cutting power. Titanium coated to reduce friction and heat. 2mm step increments. The hex shank enables the step drill to be quickly fitted to any 1/4in power bit adaptor.