Here's a Dark Cobalt Blue U-666 OB marked insulator in excellent condition. Not shown in this color on NIA website. Similar to U-665 but notice the U-666 has the squared ears. I've seen many of the U-665 in a medium blue but this is the only U-666 in cobalt I have seen so they are likely uncommon to scarce. One of the first cobalt insulators I purchased over 30 years ago. No chips or cracks, looked hard and found 2-3 very tiny tic marks and one tiny base fleabite.

First email that says they want it gets this beautiful porcelain insulator for the reduced price of only $60 plus 11 shipping. Thanks