GI-70BT (ГИ-70БT) is a transmitting, metal-ceramic coaxial triode (all outer metal parts are silver plated) designed to work as an oscillator and an amplifier. It is the same tube as the GI-7BT but without the silver plated aluminium cooler (GI-70BT was intended for other type of cooling). If you have a free cooler, you can easily turn the GI-70BT to the GI-7BT tube (forced air cooling). New in box tubes. Years of production: 1986-1989 (please look at the gallery pictures).