As a US seller we stand behind our products. All vintage vacuum tubes sold by Riverstone Audio are backed by our no-nonsense 4-YEAR WARRANTY - THE BEST WARRANTY IN THE AUDIO TUBE BUSINESS! ***IMPORTANT: AMPLIFIER DAMAGE CAN OCCUR IF YOU USE THE WRONG TYPE OF TUBE AS A REPLACEMENT. 5654W tubes are a DIRECT substitute only for 7-pin 6J1, 6J1P / 6J1P-EB / 6Zh1P-EV, 6AK5, 6AK5W, EF95 and 403B tubes. For other substitutions, check with your amplifier manufacturer to verify that 5654W tubes can be used in your particular audio device.*** Package contains a closely matched pair (2 tubes) of vintage US-manufactured GE JAN 5654W vacuum tubes. The tubes are Amplitrex TESTED and MATCHED, and subjected to multiple test cycles to determine stability. Plate current and Gm are BOTH matched to within 3%. Matched tubes undergo a final audio sound check to make certain they are indeed audio quality. With our high standards, 5654W tubes were originally designed as a low-noise premium-grade substitute for 6AK5 and EF95 vacuum tubes. The "W" designation refers to ruggedized military-grade tubes with better quality control and internal design changes to enhance reliability. These vintage tubes have found new life as replacements for 7-pin 6J1, 6J1P (6ZH1P-EV), 6AK5 and EF95 tubes and are commonly used by audiophiles for improved sound quality. When received, we guarantee the tubes will test at NOS levels of 4400 micro-mho or higher and a plate current (ip) of 6.4 mA or higher (tested in fixed-bias mode at a plate and screen voltage of 120 V and a grid voltage of -2.0 V). NOTE: Some amplifiers, such as the Little Dot 1+, MK II and MK III, may require circuit board jumpers to be changed when swapping tubes (procedure is outlined in the Little Dot manual). All vacuum tubes we sell are carefully packed for shipping and will have the "Riverstone Audio" name, logo and QC labels on the boxes.