Here's an oddity! There is a large 1-1/2 " by 3/4" chip on the wire ridge that was glazed right over, and then a large piece of porcelain stuck between the inner and outer skirts underneath. Could be possible that the piece stuck is from the chip! There are no markings on the insulator. There is one small peck from the wire ridge on the chip and another small one on the other side. Other than that, it's in very nice condition and the glaze color is beautiful! Take this unique porcelain signal for only $16 + Shipping. Priority mail shipping preferred. PayPal accepted, USPS Postal Money Order preferred.