This is a Groove Tubes 12AX7-R vacuum tube, which was acquired by Fender. I purchased this about 10 years ago as a replacement tube for amplifiers and effects units that use vacuum tubes. I used it a few times as a replacement, but I never used it permanently for years. After that, I stored it because I had no opportunity to use it due to the advancement of digital technology. Here is the product introduction page from the import agent CFE at the time: ////////////// The R2 tube has a longer plate among the R series vacuum tubes, and it is characterized by a thick low-frequency range and a bright tone. If you feel that your amplifier is a little dark, inserting this vacuum tube will give you a brighter sound. Made in Russia. Customer Reviews: "The high frequencies were a bit too prominent before, but after replacing it with a 12AX7R2, the high frequencies were suppressed to just the right level, and it became a thick, round jazz tone, giving the sound a tighter feel."