This sale is for ONE (1) EM84 / 6GF6 Mullard Tube. Hickok 539B Tested and. All tubes have been tested and matched on two Hickok Professional Tube Testers. PreAmplifier and Power Tubes are tested on a NEW DIGITAL Maxi Matcher PreAmp II Tester, and a NEW DIGITAL Maxi Matcher Power Tube II Tester.