Heller prefix hss metal drill bits heller 27424 1 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 singly heller 27424 1 0911 prefix hss metal drill bit 65 x 63 x 101mm