a flexible wire , that when inserted through pre-drilled holes in the head of a nut , bolt or union , would be twisted tightly to form a stronger , more rigid wire , and then threaded through the opposite part of the union , preferably at a right angle , pulled tight ( in theory pulling the nuts even tighter ) , and then twisted for a further half an inch , snipped off and the end folded back on itself and pushed flush with the nut .