An older service pin for Socony Vacuum, the company that later became Mobil Oil. This is a silver pin with Pegasus the horse done in red enamel with the words Socony Vacuum underneath. Very nicely detailed and it looks like sterling silver, although it's not marked so I can't say for sure. It has a nicely working locking clasp.
It measures 1/2 inch long and is in excellent condition.