Offered is a NOS 6SL7GT branded Zenith, made by Sylvania. The tube tests good on the Jackson dynamic tester and it shows no shorts or inter-electrode leakage. The tube has robust triode readings of about 110% and 110% where the good range goes from 70% to 130%. The tube has dark grey plates and a lower getter with good silver flashing. Production code on the black bakelite base: 113 code on glass below designation: K6M. Suitable for audio amps and radios too. Pick up the tube for your own Zenith Hi Fi. Mouse over the photo images to zoom in. NO RESERVE!! Thanks for looking.