Vintage soviet beam-power tetrode GU-13 (ГУ-13) with maximum anode dissipation of 100W. It is direct replacement for the american 813 tubes (by the way the older versions of the GU-13 were marked as 813 as well) and also for the chinese FU-13. New old stock, directly from the old reserves (please look at the gallery pictures). Made in the early 60's.