This listing is for a laboratory-matched pair of RCA VT-139 / OD3 voltage regulator tubes. These are authentic military-grade tubes manufactured for the Western Electric Co. and the U.S. Army Signal Corps in 1941. This specific early production features the robust Round Grey Plate structure and Bottom Double Square Getters.

Both tubes are housed in their original government-issue (GVT) heavy cardstock boxes, marked with Order No. 6375-NY-41. As 150V gas-filled regulators, these are critical for stabilizing power supplies in high-fidelity audio equipment, ensuring consistent voltage and reducing noise floor.