A CD 156.1 base embossed POSTAL TELEGRAPH CO AT SEP 1 (backward 3) 1881.Because of an open bubble on the base, the letter P in PAT is missing. The color is a light green. There is a shallow skirt flake associated with the open bubble. Also a shallow chip (1/4" dia.) above the wire groove, a little roughness along the upper ridge of the wire groove, and a dull spot (about 1/4" dia.) on the dome. All that said, it's still a pretty good insulator and I've priced it way low. Looking for $35 plus shipping. Check, money order or PayPal, no fee.