MG 1Shield Brand MG 1 Custom Fit Mouthguard Get personalized protection with the MG 1 Custom Fit Mouthguard from Shield Brand designed for athletes who demand a secure, tailored fit. Using a simple mixing process, the included powder and liquid are combined with the wooden spoon provided to form a pliable material. This mass is then cast directly to your teeth, creating a custom molded mouthguard that adapts perfectly to the unique shape of every tooth.