Electron tube SG3S (СГ3C) is a soviet voltage regulator. Stabilized voltage in the operating current range: 108,5±3,5V. Operating current: 5-40mA. Filling: argon-neon. SG3S is direct replacement for the similar types OC3 and VR105/30 (technical parameters are close to identical, OC3 and VR105/30 do have another bulb shape). Service life guarantee: not less than 1000 operating hours. Original enclosed datasheet is available for download. New in box tubes, directly from the factory packing. Made in the 60's.