Here is a mid-century vintage CLEAR GLASS TELEGRAPH INSULATOR in the 'CN' STYLE BY PYREX. Very clean, internal threads seem perfect, plenty of other markings around lower rim, excellent condition, no chips or cracks. Made in USA. (Priced Individually).
GLASS TELEGRAPH INSULATORS were used to prevent electricity from flowing from wires to supporting structures like poles or towers, ensuring the safe and efficient transmission of power and telecommunication signals.
DID YOU KNOW? Pyrex (trademarked as PYREX and pyrex) is a brand of glassware originally developed by Corning Incorporated. Pyrex was first introduced in 1915 as a line of clear, low-thermal-expansion borosilicate glass whose resistance to chemicals, electricity, and heat made it ideal for laboratory glassware and kitchenware.
