Centering ears and locking barbs prevent release under stress or vibrations. Spring arm thickness compensators keep bundle tightly anchored in panel up to .125" (3.175 mm) thick. RTPM-657 push-mounted head snaps into .25" (6.35 mm) hole, providing one-piece mounting and bundling. Smooth, rounded edges do not cut insulation - or hanrds - and are comfortable to work with.