Heller prefix hss metal drill bits heller 26892 9 this prefix universal drill bit from heller is a reliable metal drill bit ideal for unalloyed steel and non ferrous metal this 6 x 57 x 93mm bit has a web thinned centre point for accurate bit positioning supplied in packs of 10 heller 26892 9 0911 prefix hss metal drill bit 60 x 57 x 93mm pack of 10