The 122P224 Nixie tube (or B5092A) was made by Burroughs of the United States, so this is a genuine branded Nixie tube. This tube is special because it has Krypton 85 added, which is a radioactive isotope of Krypton that emits alpha particles. These keep the Neon ionized and so help reduce the time it takes the tube to ‘ignite’, especially in dark conditions.
This is a very common form factor – there are many other Nixie tubes with the same digit size, envelope size, socket type and pin assignments.
Bell Labs safe handling notes:Kr85 Notes