VIZION 12AX7 VV vacuum tube. I can't find the VIZION company, so I think it's a discontinued product. High-gain model, low-frequency & power up 20%, made in China. I bought it about 10 years ago as a replacement for amplifiers and effectors that use vacuum tubes. I used it a few times as a replacement, but I didn't use it permanently for years. After that, due to the rapid advancement of digital technology, I had no opportunity to use it and kept it in storage.