This looks like a capacitor bushing to me.11 ribs that alternate from wider to shorter to wider to shorter. The base has 2 screw threads and a rubber seal. Rust on a couple of the ribs. About 1.25" indentation in the base, light corrugations on the base, 0.3" thickness of the base, 4.2" tall. No chips or dings. $20 plus postage.