Special and rare soviet ceramic tube sockets BT4.816.000 (БТ4.816.000) with metal construction. Sockets are suitable and designed for the GU-50 (ГУ-50) tubes. New old stock sockets in nice condition (with some small scratches and color abrasions at some places, especially on the top of the construction). Generally very nice and especially original vintage soviet tube sockets (please look at the full gallery for more details).