The promoter must have--at ringside--an adequate supply (not less than six) sterilized mouth pieces that can be formed to fit.
No boxer shall be permitted to perform in any contest without wearing a form fitting mouth piece. It is suggested that each boxer have a spare mouth piece in the event the one he/she is wearing breaks. Boxers are not allowed to share mouthpieces.
S.C. Code Regs. § 20-2.16