Heller prefix hss metal drill bits heller 27420 3 this prefix universal drill bit from heller is a reliable metal drill bit ideal for unalloyed steel and non ferrous metal this 45 x 47 x 80mm bit has a web thinned centre point for accurate bit positioning supplied in packs of 2 heller 27420 3 0911 prefix hss metal drill bit 45 x 47 x 80mm pack of 2