Heller prefix hss metal drill bits heller 27417 3 this prefix universal drill bit from heller is a reliable metal drill bit ideal for unalloyed steel and non ferrous metal this 3 x 33 x 61mm bit has a web thinned centre point for accurate bit positioning supplied in packs of 2 heller 27417 3 0911 prefix hss metal drill bit 30 x 33 x 61mm pack of 2