Upgrade tube Set of Four NOS Tubes for any 6P1 / 6J1 ampTested and Measured Pair 6J1P-EV Pentodes (6Ж1П-ЕВ)Old stock. The tubes are new and never used”Voskhod” factorySame Date code”OTK” markedMilitary rhombus+ Tested and Measured Pair 6P1P-EV (6П1П-ЕВ)Old stock. The tubes are new and never used”Svetlana” factorySame Date code”OTK” markedMilitary rhombusWe test our tubes from this type on High-End Soviet Military Tube Tester: L3-3Measured parameters attached to each tube, difference < 3%on the photo shows an example of tubes with parameters, if you need actual parameters, please askVery careful packingLot of 4 (Matched & Balanced Pair 6J1P-EV + Matched & Balanced Pair 6P1P-EV ) The Same Tubes with shipping from the USA:US Stock 6P1 pair + 6J1 pair (4pcs) Matched & Balanced Tubes Upgrade 6P1&6J1 amp Shipping:All orders will be shipped by airmail with a tracking number.I will combine an orders and send you an invoice with a total (less expensive) shipping cost.