These 12AT7 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. Durable phase splitter or driver tube. Excellent in vibrato or reverb circuits where consistent, high output power is desired. Please note that tube sales are final. • MFSKU 5550112400 • UPC 736021124004