One pair, 7-pin 6J1P-EV (6Ж1П-ЕВ) Fully-Tested and Matched Vacuum Tubes. Matched within 3% match for BOTH ip and Gm. These vintage Russian vacuum tubes, provide high audio fidelity and can be used as a direct replacement for 6J1, 6J1P, 6AK5, 5654W, 403B and EF95 vacuum tubes. The -EV suffix (-EB in cyrillic spelling) designates a military-grade long-life version of the standard-grade Russian 6J1P (6Ж1П) vacuum tube. 6J1P-EV (6Ж1П-ЕВ) vacuum tubes can be readily identified by the three vertical grooves moulded into the glass shell, a saucer-shaped getter holder and the horizontal Voskhod "Rocket" logo printed on the tube directly above "6Ж1П-ЕВ" and the manufacture date (see listing images for futher details). Chinese-manufactured 6J1 tubes will not have the glass grooves and will have a rectangular getter. As with vintage US-manufactured 5654W vacuum tubes, true NOS 6J1P-EV tubes are becoming increasingly difficult to obtain in sufficient quantities to allow the matching of test parameteres. Fortunately, a decade ago, we purchased and stored a large quantity of 6J1P-EV tubes and are now selecting the best of these for our tested and matched pairs. Prior to matching, the tubes are rigorously tested (plate current (ip), mutual conductance (Gm), gas/noise) using Amplitrex AT1000 tube testers. Please note that the test results we provide (plate current and mutual conductance) correspond to results obtained using Amplitrex AT1000 testers; other test units can provide higher or lower measured values. For the 6J1P-EV tube, ip will typically be higher if tested on the Russian L3-3 or Chinese GS-5A tube testers, which utilize much different test circuits and test parameters. Comparision tests we have made with our in-house Amplitrex, L3-3 and GS-5A test units, and using identical sets of 6j1P-EV tubes, the L3-3 and GS-5A will show ip values approx. 0.5 mA to 1.2 mA higher than the Amplitrex AT1000 - identical tubes tested on different testers, but different internal circuits, test parameters and NOS-range for ip and Gm.