The JJ 5U4-GB tube is another affordable replacement rectifier tube for both guitar and hi-fi tube amplifiers. Installed height of 4 1/8"
NOTE: If the kit includes more than one POWER TUBE, then they (the power tubes) will be APEX Matched. NOTE: Some tube Acronyms are interchangeable - for instance: 12AX7 is the same thing as ECC83; 12AT7 = ECC81; GZ34 = 5AR4. There are others, but these are the most notable.