Suitable for alloyed and non alloyed steel up to a tensile strength of 900 nmm malleable cast iron sintered iron new silver copper bronze and hard plastics such as perspex enables up to 40 faster drilling than comparable drill bits with 118 drill bit tip and no split point the lowest possible level of friction due to titanium nitride coating which effectively reduces friction deposits note do not use in aluminium only work with cooling agent 25 piece probox metal drill bit set hs