Vintage LeadMaster No 31 mechanical pencil, drafting tool lead holder Dietzgen / Vemco

Vintage Lead Master No 31 drafter's mechanical pencil, in nice condition The lead holder jaws are operated with the push button on the end. We've been told that this pencil is either a Deietzgen or a Vemco, but is isn't marked.

There is a small spot of rust on the pocket clip (show in the last photo).