Abstract: An improved bolt which has a head with a plurality of sharp projections extending in the direction of the shank so that the head can bite in and lock the bolt to a workpiece. A second embodiment utilizes a plastic encapsulation over the head, for example, for use with buildings wherein the openings through which the shank passes is to be sealed and in this embodiment the sharp projections cut through the plastic encapsulating material so as to bite into the workpiece and such cuts are spaced so that the edge of the encapsulating material is not completely separated from the main portion of the encapsulating material.