The 2 inch (5 cm) (outside diameter; inside 1.5 inch ~ 3,8 cm) ring is made of Heavy Duty plastic while the strap is made of soft leather. The ring fits into the mouth behind the teeth and the strap buckles behind the head. The strap is very adjustable for pulling the ring into the mouth for different comfort levels.Will keep the sub’s mouth open for water sports or (almost) any other thing you want to shove down their throat. Looks good as they can’t close their mouth no matter how much they want to.