Ok...here goes...not a very large item
Large end is 5/8" in diameter, narrow part is 7/16", hole seems to be 3/16"
Large end has knurling, and the end is champfered ....the small end ?
Has a perfectly round dimple...only markings on this D. T. 1 1
I haven't a clue as to what, when, or where this was for.
Good luck..