HJC V31 Helmet Solid Size Medium (Tall) SIZE CENTIMETER HAT SIZE INCHES WPSCFC010 S SIZE CENTIMETER HAT SIZE INCHES X Small 53 54 6 5 8 – 6 3 4 20 7 8 – 21 1 4 Small 55 56 6 7 8 – 7 21 5 8 – 22 Medium 57 58 7 1 8 – 7 1 4 22 1 4 – 22 7 8 Large 59 60 7 3 8 – 7 1 2 23 1 4 – 23 5 8 X Large 61 62 7 5 8 – 7 3 4 24 – 24 3 8 2X Large 63 64 7 7 8 – 8 24 3 4 – 25 1 4 3X Large 65 66 8 1 8 – 8 1 4 25 5 8 – 26 4X Large 67 68 8 3 8 – 8 1 2 26 3 8 – 26 3 4 5X Large 69 70 8 3 4 – 8 3 4 27 1 4 – 27 5 8 00 57 58 Large 7 3 8 7 1 2 23 Advanced Fiberglass Composite shell: A composite shell designed to balance strength The V31 is an open face helmet certified to meet U