Russian IV-18 vacuum fluorescent display clock
These vintage tubes are still available in reasonable quantities and at not too outrageous prices on ebay.
VFDs need a voltage of around 40-50 volts to light the multiplexed display. Only one number is lit any time, thus each is only on for an eighth of the time. They also need a filament voltage which ideally should be AC to get even illumination across the tube. Nice, bright, large, digits and I think very attractive.
Hard to photograph due to the rapidly flashing display – too fast for the human eye but not the camera.
I made up a small board that mounted behind the tube and made a curved case, inspired by some of the simple industrial design Dieter Rams undertook for Braun.