H-D SANCTION HELMET Lightweight full-face helmet offers comfort and protection for riders who want a smaller overall size and profile. SIZE GUIDE SIZE CM IN HAT SIZE (IN) XS 48-51 18 7/8" - 20 1/8" 6" - 6 3/8" S 52-54 20 1/2" - 21 1/4" 6 1/2" - 6 3/4" M 55-57 21 5/8" - 22 1/2" 6 7/8" - 7 1/8" L 58-60 23 1/4" - 24 5/8" 7 3/8" - 7 1/2"