I have no idea.

That looks like a pipe vise jaws that you slip into a bench vise.

I'm with Ken - they do appear to be vise jaws of some sort.

I agree, though I have not seen them.

It may go on a splined shaft and a bolt tightens down for torque.  bob w.

They look very much like pip holding inserts for a vise.

Ken W. is right, they are pipe jaws for a bench vise.  Because of the rounded top to the cut out, they will fit a vise with an exposed screw.  The cutout is to straddle the screw.

Would anyone like to have them?

Pipe Inserts for vise.  Here is a pretty good picture.

http://www.ebay.com/itm/SUPERIOR-ERIE-TOOL-WORKS-ERIE-PA-USA-BENCH-VISE-43-1-2-REMOVABLE-PIPE-JAWS-/190719621604?pt=BI_Tool_Work_Holding&hash=item2c67c679e4

eBay no.  190719621604