Hey guys, it took a few emails from you to make me realize that you may wonder about the uses of Chinese thumb rings or manchu thumb rings. 

As you may know, a thumb ring is a piece of equipment designed to protect the thumb during archery. This is a ring of leather, stone, horn, wood, bone, antler, ivory, metal, ceramics, plastic, or glass which fits over the end of the thumb, coming to rest at the outer edge of the outer joint. Typically a flat area extends from the ring to protect the pad of the thumb from the bowstring; this may be supplemented by a leather extension.

This is a regular thumb ring and its knocking for archery

And this is a manchu thumb ring and its knocking

Many suggest that Chinese thumb rings or manchu thumb rings can give you faster release, while protect your thumb at the same time.

Here's a video that'll give a more direct idea of their use in archery: https://youtu.be/FeHNFtys0d8  

If you want to read more about them, like their 4000 year history and value as accessories and so on, check out this article: https://www.asianart.com/articles/rings/index.html   (You'll be surprised by how much they're worth)