A bolt for securing timber to any other material, comprises: a bolt head with a series of spiked teeth on its underside; a cylindrical bolt rod extending from the bolt head is threaded and split into two rods at its free end, so as to define a slot therebetween. In use a user drills a hole through pieces of timber to be secured together, and hammers the bolt through the hole. The spiked teeth on the bolt head lock into the timber, securing the bolt at one end. At the free, split end of the bolt rod, a washer and nut are tightened onto the bolt. A cold chisel is hammered into the slot between the split ends of the rod, bending the ends outwards and thus preventing the nut from loosening.

A locking washer for use with a screw-threaded fastener (71), said locking device comprising a first disc-like body (12) comprising an annular portion (13) with at least one aperture (15) therein and a central through-hole (14) e.g. a washer having notches (15) open to the outer or inner periphery and at least one further body (25) held in said one aperture (15). The further body may be a shim (22) also having a central hole (24) and at least one tab (25) extending through the notch (15) and has an end portion which juts above adjacent surface of the washer to engage a surface on the fastener when, on tightening of the fastener, deflects within the void of its aperture under tightening of the engaging surface such that under any tendency to loosen, the tab jams against the opposing surfaces and resist loosening of the fastener.