Our helmets have excellent protection performance. We also have a professional online service team, the first time for you to solve the problem, so that you have no worries. ? Product Details: Type: modular bluetooth helmet Modular bluetooth helmet. Material: ABS Rugged ABS shell. Cushioning layer High strength EPS cushioning layer Weight: 1600 grams Size: XS (53 ~ 54 cm S (55 ~ 56 cm), M (57 ~ 58 cm), L (59 ~ 60 cm), XL (61 ~ 62 cm) Safety certification: DOT/ECE Scope of application: Neutral and neutral four-season general use Recommended use: for motorcycles, cruisers, touring bikes, bicycles and scooters Bluetooth parameters 1. Bluetooth version: V5.0+EDR 3. Transmission distance: 10M 4. lithium battery: 3.7V/500mA 5. Charging time: 3 hours 6. Standby time: about 240 hours 7. Continuous working time: about 32 hours Packing Motorcycle helmet*1 Bluetooth headset*1 Sweat-absorbing headgear*1 If you are satisfied with my product, I hope you can give us a rating. This is not only important to me, but also to other friends who need this product. If you have any problem, please contact us in time, we will solve your problem within 24 hours.