Groove Tubes GT-EL34M - EL34 Quartet (Twin-Pack) The GT EL34M is based on the original Mullard EL34 of the '60s -the stock tube in most early Marshall and Hiwatt amps Big, fat and well-defined tone and really "wakes up" reissue amps to perform like the originals Classic "British Sound" Hand Tested & Matched in Quartets (a set of 4 tubes) Limited Warranty Included