This is a SYLVANIA 12AX7WA vacuum tube for the US military. The WA mark indicates a low-noise, high-performance vacuum tube resistant to vibration, primarily used in communication equipment, high-end audio, guitar amplifiers, and the like. I am listing this for sale to clear out my inventory. I have tested it in a real device to confirm that it produces sound before listing it. It is a beautiful product, almost unused. Please take a look at the photos and consider it for your amplifier's EQ, etc.