CD 110.5 NATIONAL INSULATOR CO. (Dome) Pointed Dot (Base) + NAT. INSUL.CO. + / PAT MAY 1. DEC.25. 1883. JAN.1. OCT.7.1884 This style has the segmented threads one very small flea bite on the top spiral and a very, very small open base bubble above the 2 in 25. Still a very desirable insulator at only… $85.00… plus postage, (Insurance is optional/extra). Buy with confidence! We do not sell altered insulators. Don't wait for a sale it's not going to happen.