This vintage glass item is a Hemingray 42 clear glass insulator, historically used to support telegraph and telephone wires.

Brand/Maker: Hemingray.

Model/Type: Hemingray 42 (also known by the CD 154 classification).

Features: It features a clear glass body with a prominent embossed "MADE IN U.S.A." marking.

Usage: Commonly used on utility poles to resist electrical flow while holding wires in place.