Generally, size MD = Youth (age 8-12) and size LG = Adult (age 13+). Built for full-to-moderate contact sports, such as wrestling, field hockey, basketball, martial arts, and soccer, this advanced mouthguard cushions and protects teeth. BiteFlex™ absorbs energy to reduce impact to the jaw. Interchangeable ArmourPlate™ insert delivers enhanced protection. Contoured EVA ensures optimal fit and comfort when you"re in the thick of it. Patented retention polymer shrinks for a secure, locked-in fit. Patented anti-microbulent secretes to help prevent the growth of germs, keeping your mouthguard fresher, longer. Dental warranty of $13,500. Includes fitting tool and UA mouthguard strap.