I saw this insulator at an auction in Berryville, Va. last Monday. It had a flat circle on top like some of the CD 731's. The circle was slightly recessed into the top almost like someone had inserted a flat coin or something into the mold before pouring in the molted glass. It was an online auction and I didn't bid when I got back home because most of the insulators were too common or wacked. This one was wacked, but I thought the circle was interesting. I didn't really take note, but I think it was a CD 121, but it could have been a CD 122. Sorry for the poor photo. I took it with my sorry cell phone. I have a smart phone on order and it should arrive next week.