In a tiny collection of commons I purchased (just for this piece), the spool stuck out to me. Not having seen another one like it before, I bit the bullet and spent a couple of bucks.

Does anyone know anything about this insulator? It is totally unmarked and I cannot discern any features which would point to a certain manufacturer.

Bill Snell was kind enough to send me a link to the Jan. 2000 PIN column in Crown Jewels: http://www.cjow.com/archive/article.php?month=1&a=01Porcelain Insulator News.htm&year=2000

While the spools in question aren't the same, I think the ones referenced in the magazine might be mounted the same as the one I have was.