What is this?

[Bill ThompsonNM]

So I'm cleaning my workshop and come across this. I vaguely remember buying it at one of the Woodworking Shows in Massachusetts maybe 20 years ago. Must go with some Tablesaw jig...but for the life of me I don't remember what.. Can anyone identify it?
two views, sort of high density poly on the whit pats (0r nylon?) and two runners on what I think is the bottom. About 7-8 inches each dimension. Here's the pictures.

[glenn bradley]

Push block that straddles the fence?

[Richard Coers]

Reminds me of the push block that comes with the Incra router fence, but it doesn't hook over anything like that. It does have the two runners like that so you don't clip the router bit on through cuts.

[Mike Wilkins]

I have one of those. Got it at a woodworking show in Atlanta, GA back in the mid to late 80's. Came with a router fence made from the same material (that I still have also). The dovetail shaped tenon on the 90 degree push fence fit into a dovetailed groove on the fence top, to keep it aligned at 90 degrees to the fence.
You would use it to make various joints with it. The fence was attached to the Incra Jig and moved in exact amounts to make fancy joints like dovetails, double dovetails, etc. I believe it was the predecessor to the modern day Incra Jig system. Mine is collecting dust since I have 2 or 3 router fences around the shop.
Keep looking; you might find the fence around there somewhere.

[Bill ThompsonNM]

I have one of those. Got it at a woodworking show in Atlanta, GA back in the mid to late 80's. Came with a router fence made from the same material (that I still have also). The dovetail shaped tenon on the 90 degree push fence fit into a dovetailed groove on the fence top, to keep it aligned at 90 degrees to the fence.
You would use it to make various joints with it. The fence was attached to the Incra Jig and moved in exact amounts to make fancy joints like dovetails, double dovetails, etc. I believe it was the predecessor to the modern day Incra Jig system. Mine is collecting dust since I have 2 or 3 router fences around the shop.
Keep looking; you might find the fence around there somewhere.
That's probably it, I do have some Incra stuff around somewhere. Clearly more cleaning to do.

[Gary Herrmann]

I have yet to find anything in my shop that I can't identify, but I'm sure it's coming.

[Ole Anderson]

Yesterday I ran across two dust collection attachments I have no idea what they fit. Neither one fits any of my hoses either, so I didn't spend much time searching for the right tool..