These are a series of jaws designed for use with Wilton Tool Co. 3" bullet vises. Mine in particular is from either 1941 or 1942 but it should work with any made during the initial design run.
Included are:
I made these just as prototypes to test out before getting metal versions made by a local machine shop, but there's no reason you couldn't use them as soft jaws.
The author hasn't provided the model origin yet.