you are buying Traditional bow thumb rings. it was hand made by workmanship. male thumb ring is more easy to pull string and no pain on finger and no slippery. you need to check width of your thumb joint as picture posted and choose your size. if you don't know exact your size, buy smaller one and grind inside by sandpaper or grinder.
Material: Genuine Korean cow horn.
This item can be sold in case your total order price is more than USD50
How to use Thumb ring wedge;
Male thumb ring includes leather wedge to tighten ring and your thumb in case thumb ring hole is larger than your finger.