These Numitron tubes are from Russian cold war era NOS (New Old Stock). As supplies of these tubes dry up, their value will increase steadily until they are gone forever! This may well be your last opportunity to build a useful project showcasing this beautiful cold-war era component.
The Numitron is not a traditional tube (valve) in that there is no electron emission involved; it only has filaments, and as such is more analogous to the light bulb than any other electrical device. Seven small filaments are arranged in the traditional formation of the seven-segment LED numerical display (See inserted in image for filaments in their "lit" state). The Numitron IV-9 operates on five volts at about 23 mA per segment. It has "fly leads," and as such does not require a difficult socket.
Numitrons also do not suffer from some of the shortcomings of Nixie tubes. For example:
They are low-voltage devices so, unlike Nixie Tubes, you do not need to insure carefully insulated enclosures to keep users from getting a nasty high voltage “bite”
They do not suffer from failure states such as the “sputtering” where electrode metal collects on the inside of the glass tube dimming or obscuring the display
They don’t encounter Cathode Poisoning that requires a potentially distracting anti-cathode poisoning software routine.
In many cases, Numitrons will outlast nixie tubes as they are typically rated for over 100,000 hours (11.5 years) of operation compared to some nixie tubes that are rated for only 5000 hours (200 days!).
All in all, Numitrons are a fun and interesting item and are perfect for building quite a remarkable clock.