Medical-grade EVA is used specifically because it softens at boil-and-bite temperatures without losing its shock-absorbing structure once set — a cheaper EVA grade can either not mold properly or lose density after the fitting process.
Academies buying in bulk for new-student starter kits are the most common order type, since a branded carry case included with each unit adds a low-cost retail touch to a required safety item.
Rinse in cold water after each use and store in the ventilated carry case rather than a sealed pouch, since trapped moisture is what causes odor buildup in EVA mouth guards.