DescriptionFrom Mesa Boogie:The MESA® EL-34 STR 447 is a premium grade NOS-equivalent EL-34. It offers traditional EL-34 tone & feel – urgent and aggressive – and is an excellent choice for all styles of gain, especially classic rock, alternative rock & metal. This tube is true to its British origins with tight, focused low end, crushing midrange crunch and crystal-like highs.Please note: It isn’t uncommon for a grid leakage indication to appear when testing EL34s in certain tube testers. This does not indicate a failed condition for a guitar amplifier. Not all tube testers test for parameters relevant to a tube guitar amplifier.