This is a Brass thumb ring but they are avaliable is horn, bronze and other material.
When shooting Horse bows ( Scythian, Turkins, Hunnish or Mongol amongst others) properly, that means off the hand on the opposite side of the bow to that which we generally shoot, a thumb ring is essential.
This one is made of brass and performs the job as well as any I have used.
If you have a Horse bow and don't know how to shoot it with a thumb ring then I can't do better than the Master Gao Yings' description, penned in 1637
"First get the arrow nocked on the string. Place the arrow so that it is at right-angles to the string (not pointed slightly downward.) Draw the arrow back one inch on the string and grip the arrow shaft with the bow-hand fingers like holding a pen. Now the arrow will be held firmly by the tension of the string and you can move around freely with the arrow nocked and held in one hand. Use the string-hand forefinger and the string itself to make a final adjustment to the thumb-ring so that it is comfortable at the base of the thumb, then hook the thumb around the string with the string at the bottom of the ring, adjacent to the base of the thumb. Curl the index finger around to support the thumb just behind the nail. (Not on the nail itself. And ensure that the nail is cut short!) Curl the remaining three fingers back and press them lightly into your palm. Lower both arms so that the arrow is pointed forward at the ground about metre in front of your feet; take the strain of the string, drawn about an inch, back from the bow-hand fingers and re-arrange the bow-hand fingers as described above. Relax your body completely and clear your mind".
Features & Design
Simple Brass thumbring, I have seen and used more decorative ones but the basic shape is good.
It does it's job without fuss.
Value for Money
Quite expensive as there are many available for half this price.
It is a solid piece of kit