Another less expensive widely used registration nut Acorn Nuts are installed between the two halves of an unvulcanized rubber mould to insure the proper orientation of the two halves. Because of their six-sided configuration, acorn nuts have a holding ability superior to any other form of mould locator.
 
Available in Packs of 100 250 and 500 from stock
 
a =   6mm
b = 10mm
c = 10mm