Commonly called mechanical pencils, these make sketching or writing in the field clean and easy. Leads can be inserted into either end, just slip the ring down to tighten around the lead. These are handmade out of brass.
Small: 4" long - single-sided lead
Large: 7" long - double-sided lead.
I purchased six dice and a mechanical crayon. They are wonderful and very nice and useful
It looks to be well made. It writes well and is way better than using a pencil nail. I should have ordered an extra lead with it.