A Chinese copy of the Sovtek 12AX7WBA, lower gain, quiet, commonly used in Blackstar and Loud amps.
All Ruby Preamp Tubes are tested by Magic Parts™ for quality assurance and selected for low microphonics and hum. This ensures that even the highest gain tubes will be quiet and dependable. Ruby Tubes come with a 6-month manufacturer's warranty.
HG standard grade will work in all positions in an amplifier, usually the first gain stage in a low or mid gain amplifier.
HG+ is for use in high-gain amplifier circuits.