This is a free website I started over a decade ago designed to teach and empower you to make your own perfect custom made thumb ring which will fit you. Take whatever information you want, it is free to all. Feel free to pass this around to anyone who is embarking on the most astonishing archery they will ever shoot.
This is a link to the finest most authoritative book I have ever read on thumb rings and thumb ring archery.
This book is a “MUST READ” if you want a profound understanding of how to be an outstanding thumb ring archer. I highly recommend this book. Trust me, the value is outstanding.