To upgrade or downgrade the lining of your Arai helmet, you can order the lining in different strengths. To know the strength of your actual lining, please have a look on the label which is fastened on the lining in your helmet. for Tour-X 3 and VX-3 Inner Lining (100% polyester) easily cleaned Dry-Cool Head size Helmet size Lining Code tight standard loose 54 XS II - 12 mm 10 mm 7 mm 5 mm 55-56 S II 12 mm 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 12 mm 10 mm 7 mm 5 mm - 63-64 XXL IV 10 mm 7 mm 5 mm - -