I'm not sure of the U-number for the insulator on the left. It measures exactly the same as a U-308A (3 ¼" x 3 ¾"), but the grayish brown metallic colored glaze is not listed in the porcelain price guide. The lower left photo shows the color most accurately. The porcelain appears to be dry-process, and the glaze is very uneven, mottled, and striated. Very crude. The single skirt chip shown is the only damage.

On the right is a porcelain johnny ball strain that measures 3" x 2 ½" with brown/black glaze that has a similar metallic luster to it. There are four areas of chipping around the curved edges, the largest being ¾" x ½". Also very crude.

Asking $10 plus postage for the pair.