This is a real nice original steel drive coupler for an International Harvester rotary magneto for a tractor.  It is in excellent condition with no cracks, breaks, or repairs of any kind.  This was used with the E4A magneto as used on the 8-16, 10-20, 15-30, 22-36 tractors and possibly others.  It measures 1 1/4 inches long and 1 1/2 inches in diameter with a 1 inch center bore.  The lugs and slots are 1/4 x 1/4 inch.  I believe this piece is ready to be used on a magneto. If you need one for any reason here it is.  The pictures tell the story.  It would also be a great spare on the shelf.  You'll like it.  I can be reached by phone or text message if you'd like to talk about it.  Good Luck.