I bought one on Taobao before, and then I took it to the counter for inspection, saying it was genuine. After wearing it for a while, it felt good. The feeling of neck pain in the past has also eased.

I can't remember the Taobao address. The name of the shop seems to be: Oron Zai Tian. Specializing in selling titanium germanium jewelry, you can search on Taobao.