To-upgrade-or-downgrade-the-lining-of-your-Arai-helmet-you-can-order-the-lining-in-different-strengths-Please-take-the-standard-strengths-of-your-helmet-from-the-following-table-Inner-lining-Helmet-size-Inner-lining-strengths-XS-10mm-S-7mm-M-10mm-L-7mm-XL-7mm-XXL-5mm-for-Astro-Viper-&-Quantum-V-Inner-Lining-100-polyester-easily-cleaned