Every collection should have a CD 110.5 "corkscrew" because it is one of the most unique insulators made. It is a stand out piece. The corkscrew is base embossed + NAT. INSUL. CO. + PAT. MAY. 1. DEC. 25. 1883 JAN. 1. OCT. 7. 1884 (perfect bold embossing). This one, as you can see in the photo, has segmented threads. The insulator is perfect except for a shallow 1/4" chip on the bottom ridge of the wire groove. Might find one flea bite on the very top. The glass is sparkling clean. $100 delivered anywhere in the U.S. or Canada.