Or at least I think it’s a spline cutting jig. Could be used for a lot of things. That’s why I bought it. I immediately recognized the value of being able to pass a tall board by a machine with a miter slot.
They didn’t have a price on it. I walked it up there and the tending clerk gave it to me for $5. I just about leapt out of my skin. I don’t know what one of these goes for (unbranded), but I am sure it’s more than $5
Bet it will clean up nice. I have a bunch of things with miter slots. Router table, bench grinder/sander belt/disc, bandsaw, etc.