The Mesa/Boogie EL-34 STR-447 is Mesa's very best overall EL-34 power tube. It is a premium-grade, NOS equivalent and the tube of choice in the production of all Mesa EL-34 powered models. It has a traditional EL-34 tone and feel that is very urgent and aggressive and is an excellent choice for all styles of gain, especially classic rock, alternative rock and metal. This tube is true to the crown with focused low end, crushing midrange crunch and crystal-like highs. The EL34 STR-447 offers British-style amp tone, and has excellent structural quality with exceptional consistency and reliability. Comes as a matched pair.