It's a Soviet Pulse Modulator, Thyratron Tube from the 60s/70s.....like I said many of the FABO members don't even know what a vacuum tube is!! It's hard to believe that this GIANT tube has been replaced by a microscopic spec on our current circuit boards (micro chips). I bought it to educate my kids. When I asked my daughter's boyfriend if he knew what a vacuum tube is (this guy is a 23 year old Chemical Engineer), he said "I don't know, does it control a vacuum cleaner???"