Heller prefix hss metal drill bits heller 26893 6 this prefix universal drill bit from heller is a reliable metal drill bit ideal for unalloyed steel and non ferrous metal this 65 x 63 x 101mm bit has a web thinned centre point for accurate bit positioning supplied in packs of 10 heller 26893 6 0911 prefix hss metal drill bit 65 x 63 x 101mm pack of 10