The instrument is an Octavin. It's been discussed several times, which you can find with a search on that word. It was an attempt to make a clarinet that overblew at the octave instead of the twelfth by using only a very slightly conical bore. I tried one many years ago. Here's what I wrote in an earlier thread:
The clarinet always vibrates as a closed tube. I have read (in Benade, I believe) that the clarinet reed spends more time sealed against the lay than it does open. This longer time spent closed promotes the closed-tube mode, which is why the clarinet sounds as it does and overblows at the twelfth. During the time the reed is open, the vibration remains in closed-tube mode, since any open-tube vibration is overpowered by the longer-lasting closed tube vibration.
An instrument can produce a stable tone only when it reliably acts as a closed or open pipe. The clarinet is designed to stay firmly in the closed-tube mode, just as the saxophone is designed to stay firmly in open-tube mode. A sax reed seals completely against the mouthpiece just as it does on the clarinet, but for a shorter time.
There have been attempts at an intermediate instrument, with a slightly conical bore that balances the open and closed periods, or falls just barely on the open tube side, but they were unsuccessful. A number of years ago, at the late, great Ponte's music store, Charlie Ponte brought out an early 20th century instrument called "Octavin," which had a clarinet setup but a bore just conical enough to act as an open tube and overblow at the octave. It was difficult to play, and sounded more like a saxophone than a clarinet. When I tried to make a clarinet sound, it quit playing altogether.
Octavins appear on eBay several times a year, usually priced at over $1000. They're uncommon, because they were unsuccessful, and little or no music was written for them. If you bought one, it would be as a collector's item, and to astonish your friends, and not because you might find a way to perform on it.