Commodity name: Motorcycle bluetooth helmet★European Union: ECE R 2205 certification helmet★United States: DOT standard certification helmet, FMVSS-218★Helmet material: ABS★Product net weight: 1500 grams★Features: helmet high strength, light weight, impact resistance, smooth, breathable, Bluetooth★Ventilation: upper and lower vents to facilitate air circulation in the helmet★Sun visor: PC material, adjustable, anti-ultraviolet, wear-resistant★Lining: removable and washable waterproof quick-drying lining to meet all the needs of long-distance travel.★Waterproof: Bluetooth host silicone all-inclusive waterproof design★SIZE:XS=(53-54CM),S=(55-56CM),M=(57-58CM), L=(59-60CM), XL=(61-62CM)Brand Service: STTTBD★ If you have any questions or dissatisfaction with the helmet, please contact us and let us solve this problem perfectly through friendly communication.★If you are satisfied with my helmet I hope you can rate us. This is important not only to me, but also to other friends who need this product