GT-12AY7 tubes pass every Groove Tubes premium certification for microphonics, hum, physical characteristics and function. Quite simply the best 9-pin triode preamp tubes you can buy - specifically designed and tested for musical instrument amplification and standard equipment on Fender® amps. Outstanding and consistent performance for mixing and matching to get a signature tone from your amp. Low-gain tube used in very early Fender amps. Great for harp or blues where softer, more compressed distortion at lower volumes is desired. Can sub for a 12AX7 to lower gain and produce a warmer tone. FEATURES 9-pin triode design Lowest gain preamp tube offered by Groove Tubes Lower gain than 12AT7 for warmer tone Medium/soft gain Made in Slovakia