Amazing rugged full wave rectifier tubes manufactured in the United States by renowned Cetron. These Mil. Spec. 8 pin octal based tubes have straight sided thick glass envelopes and huge cup shaped industrial gray bases. Ideal for high current applications, these tubes come with black plates, four thick metal posts, and double side getters. They are printed on base with Cetron logo, CETRON JAN 5R4WGB MADE IN U.S.A. with various codes indicating early 1970's production.