Thumb Armor by Elong Outdoor.
A leather thumb guard with brass inlay, so you get the comfort of a leather protector, but the stiffness inside of a thumb ring. Elong states that it is for beginners, but even I had a lot of fun with.
It works deep hook, but I love that you can do shallow hook with it.

elongarrow.com 



Some asked that they have problems ordering the thumb guard, this is what Kelly wrote me in an email:

I receive some emails. They can remit payment to our paypal account and we will send it for them by post.

Also sent to end users.

If they ask you, you can tell them contact: kelly@elongoutdoor.com or kelly@elongarrow.com

Or we have a shopify store, link as following:
https:nikabow.com/products/soft-leather-brass-thumb-ring-archery-finger-protector-for-traditional-reurve-bow-finger-guard-protector-shooting-glove?_pos=1&_sid=885785e83&_ss=r

If you want to see even more in dep