Unique hinged design allows easy breathing and talking, unlike boil-type or impression-type models. Open posterior area adapts easily to appliances and new treatment hardware. Patented spring-action hinge stays in place and cannot be dislodged. Cannot be swallowed with helmet strap in place. Not made with natural rubber latex. Assorted package contains 2 of each color mouth guard: green, black, yellow, blue, translucent, and red.