Mesa Boogie EL34 STR 447 tubes in pair. The MESA EL34 STR 447 is the very best overall EL34. It is a premium grade, NOS (New Old Stock) equivalent and tube of choice in the production of all new Mesa EL34 powered models. It has a traditional EL34 tone & feel that is very urgent and aggressive and is an excellent choice for all styles of gain, especially classic rock, alternative rock & metal. This tube is true to the crown with focused low end, crushing mid range crunch and crystal-like highs. This is one of favorites for authentic British tone. Excellent structural quality provides exceptional consistency and reliability