Check the listing for details. 6P1 pair + 6N1 pair (4pcs) Matched & Balanced TUBES Upgrade Nobsound 6P1/6N1 amp. Condition: New. Listed at 39.50 USD. Upgrade tube Set of Four NOS Tubes forNobsound MS-10D / 30D, Liston 12 and another stock Chinese 6P1/6N1 amplifiers.If you are not sure if this kit will fit your amplifier, please write me and I will checkPlease NOTE that Chinese manufacturers make changes to the amplifier circuitry, including replacing types of tubes without changing the technical documentation, so the best way to check what type of tubes are installed in your amplifier is to read the markings on the tube itself. Tested and Measured Pair 6N1P Double triodesWe test our tubes from this type on High-End Military Tube Tester: L3-3Measured parameters attached to each tube, difference between sections and between tubes < 5% on the photo shows an example of tubes with parameters, if you need actual parameters, please ask+Mapched pair 6P1P-EV (6П1П-ЕВ) 100% New ItemOld stock. The tubes are new and never used"Svetlana" factorySame Date code"OTK" markedMeasured 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 6N1P + Matched & Balanced Pair 6P1P-EV ) The Same Tubes with shipping from the USA:US Stock! 6P1 pair + 6N1 pair (4pcs) Matched & Balanced TUBES Upgrade Nobsound 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.