This disclosure generally pertains to various end pieces for releasably securing to a coupling element. In at least one example, the end piece may be used for releasably securing a guitar strap to a coupling element on a guitar. In various examples, the end piece can include a body having a first surface opposite a body having a second surface, a first aperture defining a first aperture opening communicating between the body first and second surfaces, and a plurality of resiliently flexible projection elements extending radially inward and spaced apart relation from the first aperture.

A support assembly for an assembly comprised of an extruded member that defines a cavity, the member including an opening having a plurality of sides, and a crush tube inserted into the cavity of the member and mechanically retained in the member at or near a desired location by flanging the sides of the opening into an open end of the crush tube.