This is a 1 digit Vacuum Fluorescent Display (VFD) clock. The clock flashes out the time every few seconds. Made with an IV-6 vintage VFD tube that I purchase from Ukraine and domestic sellers. Includes white 5 volt power supply and 6 foot USB cable. Has a blue LED that is under the base of the tube to give a nice effect. Especially looks cool in the dark. The time format is 12 hours. Time keeping is based on a 32.768 kHz watch crystal. Easy one button time setting. The base of the clock is 2.25 inches in diameter, the tube height is about 1.5 inches and total clock height is almost 2 inches. The tubes used in the clock are dated from the '80's or '90's so it is a cool vintage look. Color of display is greenish-blue. Onboard boost converter circuit raises voltage to a safe 18 volts to power tube. Designed and assembled in USA by me.