Drill bits do not get any tougher than this with hexagonal shank slip proof also compatible with bit holders suitable for use with alloyed and unalloyed steels the drill bits are made from acid and heat resistant steels gray cast iron and cast steel they are extremely temperature resistant delivering higher cutting speeds harder than carbide and titanium includes 1 drill each 1 mm drill length 23 mm total length 58 mm 2 mm drill length 32 mm total length 68 mm 3 mm drill