1 1950's NOS 6L6 Sylvania Tube - Black Plates MAXI & Hickok Tested 108% of NOS
MAXI Matcher & Hickok 539B Tested. All tubes have been tested and matched on two Hickok Professional Tube Testers. I then use the Hickok 539B to confirm the test results and provide an. Hickok's 539B Specifications state that any tube over.