NIPIT is how to stop thumb sucking for children age 2-7 . NIPIT STOPS the hand from comfortably reaching the mouth. Make finger sucking stop safely without a finger guard or thumb guards; no need to cover the hand with a thumb guard to stop thumb sucking - they collect slobber and kids chew on them!
https://www.amazon.com.au/Age-2-7-STOP-Thumb-Sucking/dp/B00VQU2DZS