This part was in a catalog of rigid conduit fittings. It is just like
a reducing bushing, threaded inside and out, but it
also has a "hex nut" flange one one end so it can be turned with a
wrench. What are these normally used for?
Another clue-- the part is a Thomas & Betts 1250. Could this be
used to enter a box that has a knockout that's
a size too big?

--zeb