Electron tube EF806S Tesla is a pre-amplifier pentode of special quality, designed to be low noise and anti-microphonic. Improved version of the EF86. High reliable tube, vibration and shock proof, tight tolerances and extra long life (over 10 000 operating hours). Made in former Czechoslovakia in year 1966. New old stock tubes, directly from the factory packing. Tested on BM215A tube tester. Will be delivered in modern white boxes.