Thought some people would like to see the different types of colored electric fence insulators I've aquired over the years. These were actual fence insulators but could have been used for radio etc. This group is of Prime Mfg. Co. nail knobs. They are marked PRIME on the top. The spool is unmarked but the design and color suggest to me it was made for them. Knox Porcelain Company made the nail knobs for Prime back in the 40's and 50's. Would be neat to see the cobalt blue ones on a fence line somewhere.