The full face motorcycle modular helmet awaits the choice of all fighters.【Product Specifications】Product net weight: 1700 gramsFeatures: high strength, light weight, impact resistance, smooth, bluetoothWaterproof: Bluetooth host silicone all-inclusive waterproof designDouble-layer sun visor: PC material, adjustable, anti-ultraviolet, wear-resistant.Lining: Removable, washable, waterproof, quick-drying lining for all your long-distance travel needs.EU: ECE R 2205 certifiedUnited States: DOT, FMVSS-218 standard certificationBluetooth parameters:1. Bluetooth version: V4.0+EDR2. Frequency range: 2.4026GHz-2.480GHz3. Transmission distance: 10M (the transmission distance varies due to environmental factors and different mobile phone Bluetooth devicesdifferent)4. MIC distance: ≤ 1 meter5. Lithium battery: 3.7V/500mA6. Charging time: 4-5 hours7. Standby time: about 180 hours8. Continuous working time: about 32 hours9. Bluetooth name: BT8【The correct measurement method of the helmet】Tools: Soft ruler or string (one size larger when wearing glasses!) Method: Use a soft ruler to measure around your eyebrowsM=50-56cm, L=57-58cm, XL=59-60cm, 2XL=61-62cm, 3XL=63-64cm【packing list】1* motorcycle helmet1*USB charging cable1* Helmet Headphones1*Instruction1* Velcro fleece surface1* Velcro hook surface