Very Nice NOS General Electric 12AX7 / ECC83 Twin Triode Tubes. ECC83 is the European designation for this tube. These tubes have grey plates and are considered to be a great go-to NOS American-made tube suitable in every application including Hi-FI and Guitar amplifiers. When you compare the quality and sound of these vintage tubes to current production it becomes obvious to buy these while they are still available. Most of these tubes have a date code of “ML” indicating they were manufactured in September of 1977. All of these tubes have been tested for your satisfaction. If you need them matched please request that in the memo at check out, there is no additional charge. Please note the boxes are a little rough.