Abstract: A cap assembly for a bolt having a head and a threaded shank with a nut threaded on the shank including a metal retainer member of substantially U-shape having a base portion and a pair of legs extending therefrom. Each of said legs has a pair of relatively sharp vertical edges thereon and a threaded opening in the base portion for threaded engagement with the bolt. A metal cap member having a top wall portion and a cylindrical wall portion is fitted over the legs of the U-shaped member. The cap and retainer are dimensioned so that when the cap member is assembled on the retainer, the legs of the retainer will be compressed inwardly slightly so that the inherent resiliency of the legs will serve to create a tight frictional engagement between the legs and the cap.