Last year I saw one of these and just loved it, but didn't buy it as I didn't know what it was. I have done some research and my understanding is that these are lightning rod insulator go-withs. It was used with the Burgoon Fancy Scroll Lightning Rods. Dated 1891, roof crest glass. It has a dovetail base that fits in the channel on the ridge of a sloped roof. I was told they were on Victorian houses.

I would like to buy some of these, any color. If you have one to sell, please let me know. If you have more information on them as you are a collector of them, please contact me. I would like to learn more.

Note: The pictures I am including I found on-line and are not mine. They are used for illustrative purposes.