This insulator is marked: PATENT / DEC 19 1971 on one side and PATENT / MAY 2 1893 on the other side of the skirt. As you can see it has sharp drip points. On the "1893" side a skirt chip removes part of the wording "MAY". Almost all of the drip points are intact. This insulator was found by Joe Maurath, Jr. and myself at the Brimfield (MA) flea market for a short sum at the bottom of a bucket of rusty B-beehives.