GT-5Y3 Rectifier Tube. Every Groove Tubes product receives premium certification for microphonics, hum, noise floor, physical operation and characteristics. Specifically designed and tested for musical instrument amplification applications as noted. Low-output rectifier tube originally used in early low-power Fender amps with tube rectifiers such as the Champ, Princeton and Deluxe models. This tube can also be used as a substitute for a 5AR4 or 5U4 for lower output levels. All tube sales are final. • MFSKU 5550114302 • UPC 736021143029