Ok, I'm a bit confused here (Doesn't take much), I have a guy trying to sell me some insulators and he sent me some photo's. There are only five I'm interested in but I'm not entirely sure they are glass even though he claims they are. Does anyone know what cd # this style is? They look to me like a U-300 porcelain as the inner skirt is longer than the outer one and I couldn't match them up to any glass cd #'s.

Edit: Answered by Brent Burger and Jim Colburn, these are indeed porcelain around the U-300 area. Thanks guys!!