Rhythm Meter, Bio-Rhythm Measurement According to the manual, it can be used for sports, health, safety, golf, games, and more. It's old, and I don't know of any others, so I think it's rare... but I don't know. Please refer to the manual for details. I know nothing about this, so I don't guarantee its effectiveness. I will not accept any inquiries. Please consider it a unique toy. Please be aware of all the above. Thank you for looking.