Based on our understanding of  the Ring found in the tomb of Queen (and general) Fuhao (approxi. 1200 BC).
 
Features of thie ring:
---Great for all kinds of bows. It is a good ring to practice the shallow hook technique or swtiching from a lipped ring to the manchu ring.
---Once you get the technique, it is ideal for heavy draw weight bows.
---Sizing tolerance: a little too big and a little too tight can both work on this ring. If you are not sure about your thumbring size, try this one.
 
Material is black buffalo horn
 
Please refer to this page to measure.