Bosch robust line metal drill bit sets hss gsuitable foralloyed and non alloyed steel up to a tensile strength of 900 nmm cast steel cast iron sintered iron malleable cast iron non ferrous metals hard plastics precision ground hss g drill bit enables up to 40 faster drilling rate and up to 50 lower feed pressure than standard ground hss drill bits with a chisel edge self centring split point drill tip means there is no need to pre punch or pilot drill up to 10 mm diameter set sizes 6pce 10pce a