Electro Harmonix is a brand owned by the American New Sensor Corporation and manufactured at the Xpo-Pul - Reflektor factory in Saratov, Russia. Their new 6V6GT beam power tetrode tube features a Tung-Sol designed round internal stem, preventing arcing, for improved reliability. This tube is OEM in many modern guitar amplifiers featuring 6V6 power tubes, and as such may be deemed the current industry standard. It is known to be a very powerful and reliable tube due to its robust construction, and can easily withstand the higher plate voltages found in many modern guitar amps. It offers great tone at an affordable price.
Open Datasheet - 6V6EH