These early, cool power insulators were obtained from a retired lineman in the Barstow, CA area. Both of these insulators are glazewelds. The U-936A has a much thicker skirt than the U-936 and is 1/2 inch smaller diameter, it also has a recessed glazeweld. The U-936 has a very light blue glazeweld and is 8 1/2 inches in diameter. The pat date on the pin insert is Dec-8-1908. So far only five of the U-936A insulators have been found, and both these are dead mint. Any informational feedback will be appreciated. Thanks for looking.