Heller prefix hss metal drill bits heller 27418 0 this prefix universal drill bit from heller is a reliable metal drill bit ideal for unalloyed steel and non ferrous metal this 35 x 39 x 70mm bit has a web thinned centre point for accurate bit positioning supplied in packs of 2 heller 27418 0 0911 prefix hss metal drill bit 35 x 39 x 70mm pack of 3