I got 34 of these little gems at a yard sale with a ton of drills. They
are 2" long, one piece, have a 1" or so pilot bit, a countersink, then a
threaded shaft about 3/8" long. Seeing the countersink, I think it
would be a metalworking or woodworking item. Looks to me to be a
countersink for a wood screw, leaving a dowel hole. Castelco, IIRC, is
the manufacturer, out of California. What are they, and what are they
worth? They are out in the shop, and not 100% of the name, but that's
close.

Steve