They were a plastic body you could put a lead in and screw out with the screw on the top like a propelling pencil, see
https://picclick.co.uk/Single-Milita...227087531.html
https://www.worthpoint.com/worthoped...ator-424002585
ones we had didn't have the clip on them as it was a fod hazard.
probably have one lying about at work still.
think they were normally red or balck