Groove Tubes GT-EL84-R Medium Quartet Amplifier Tube Once the most common low-power pentode power tube, the EL84 was popularized in early Vox amplifiers Developed by Phillips in 1953, the EL84 was originally used in tube radios before being adopted by Watkins and Vox amplifiers Classic "British Sound" Hand Tested & Matched in Quartets (a set of 4 tubes) Limited Warranty Included