Vintage Garland Twin-o-matic Pen- Pencil

Vintage Garland Twin-O-Matic Pen-Pencil 1/20 12k G.F With Refill. So, I don’t have the box for this item but I do have a vintage refill cartridge with the refill inside. Now, I have no idea how to refill or what size lead the pencil uses or even if the refill ink is dried up but it is very unique to have them together. The unit is in good pre-owned vintage condition. Again, I have not operated the item. I do not want to mess with anything and cause damage. Please refer to the photos as they are part of the description. Thanks for looking.