Bell Qualifier DLX, Qualifier, MX-9, MX-9 Adventure, Custom 500 Helmets

Manufacturer's Suggested Size Chart (Not a guarantee of fit)
Size Inches Centimeters Hat Size
XS 21(1/4) - 21(5/8) 53 - 54 6(3/4) - 6(7/8)
SM 21(5/8) - 22 55 - 56 6(7/8) - 7
MD 22(1/2) - 22(3/4) 57 - 58 7(1/8) - 7(1/4)
LG 22(3/4) - 23(1/4) 59 - 60 7(1/4) - 7(3/8)
XL 23(5/8) - 24 61 - 62 7(1/2) - 7(5/8)
2XL 24(1/2) - 24(3/4) 63 - 64 7(3/4) - 7(7/8)