Fits for RX-7V QV-Pro Head circumference in cm Helmets sizue Lining Typ Tighten Standard Looser 53-54 XS I 10 mm 7 mm 54 XS II 12 mm 10 mm 7 mm 5 mm 55-56 S II 10 mm 7 mm 5 mm 57-58 M III 12 mm 10 mm 7 mm 5 mm 59-60 L III 12 mm 10 mm 7 mm 5 mm 61-62 XL IV 10 mm 7 mm 5 mm 63-64 XXL IV 10 mm 7 mm 5 mm 63-64 XXL V 10 mm 7 mm 5 mm 65 3XL V 10 mm 7 mm 5 mm