Two claims travel with these objects and only one of them survives examination.
The instrument is real. Metal standing bells are genuine Buddhist ritual instruments with a long documented history in East Asia. The Japanese rin and the larger keisu mark the beginning and end of chanting and of sitting practice in Zen and Pure Land temples, and comparable bowls are used in Chinese and Korean Buddhism. Struck, they produce a long clean tone with an obvious liturgical function: they open and close a period of attention.
The pedigree is not. The story sold with bowls marketed as Tibetan, that they are an ancient Himalayan sound-healing technology, that their use was secret, that monastic authorities suppressed knowledge of them, has no support. Tibetan Buddhist ritual is loud and well documented, and its instruments are cymbals, long horns, oboes, drums, thighbone trumpets and the handbell. The standing bowl does not appear in it in the role the marketing describes. A suppression story is convenient precisely because it explains the absence of evidence, and it should be treated the way any such story is.
What actually happened is more ordinary. Metal bowls made in Nepal and northern India, largely as domestic and market vessels, were exported in quantity from the mid twentieth century. A therapeutic practice was built around them in Europe and North America from the 1970s, drawing on the general Western interest in Asian religion of that period. The practice is real, the practitioners are sincere, and the sound is genuinely striking. None of that requires the invented history, and the invented history does real damage, because it hangs a fabrication on a living tradition that is then expected to answer for it.