cleaning out old tool boxes in the garage, I came across this tool.
It is marked 'COMPANION Made in USA' on the top.
It has some sharp prongs on the bottom which appear to me to be for keeping some kind of material in place.
It also has instructions to 'PRY OPEN'
Numbers on the side appear to be 3-681.
Any help would be greatly appreciated.

It looks like a sandpaper holder for hand sanding.  I think the prongs held a black rubber or dense foam pad in place.  The friction on the pad and the ends being held by the holder kept the sandpaper in place.

Thanks so much for the reply.
This is what I finally decided it must be.
Appreciate the information and confirmation

Some sanders like that were designed for a long strip of sandpaper that would roll up inside the case, with new lengths of fresh paper pulled out as the old paper wore.

Ah - I have never seen sandpaper in that form, but it certainly makes the design of this tool more understandable.
Thank you for the reply!

Here is one branded Dunlap.
-Don

Oh wow - and the picture is much better, also.
It doesn't look like the Champion one ever had an actual label.
Thanks so much for this!

Companion and Dunlap were both "second line" tools for Sears: lower cost, fewer features or skimpier quality than the Craftsman tools.  But often, by modern standards, perfectly fine tools, because, well, modern standards are often terrible when it comes to hand tools.