Specification:BrandSmart4u SH55MMaterialEPS + PCShell size55-59cmLED light bead6Vents13bluetoothble 4.1 + bt 4.2Speaker2 x 0.5WCharging portMagnetic USBBattery capacity3.7V 450mAhBattery enduranceApprox.10hrs for lighting / 3-6hrs for music and lightingStandby durationMax 180 daysCharging timeApprox 3 hrsElectrical parameterDC 5V / 0.5AFeatures:1. Smart4u SH55M Black Helmet designed for Xiaomi e-scooters Smart and Safe Cycling Helmet. Take the initiative tokeep you safe- Bluetooth Phone- Stereo Speaker- Smart LED lighting- SOS Alert- Walkie-TalkieBluetooth Phone - One Button Answer2. With built-in Bluetooth 4.1 high sensitivity wireless module, wind resistant microphone for clear conversation at a maximum speed of 25km/h,you are capable os answering or hanging up phone calls with one click on the Bling jet mounted on the handlebar of the bike.Stereo speaker provides you with a pleasant and safe riding. Two stereo speakers are installed on both sides of the helmet,a safe and pleasant riding guaranteed with high fidelity music and audible surroundings.3. 6 LED Warning Lighting Beans with Patented Concealed DesignIt is the 6 high-brightnedd LED warning lighting beans,patented silk-screen printing concealed light transmitting design, as well as a visual distance over 150 meters that makes thissmart helmet a safe companion in the late night.4. SOS Trigger in the event of an accidentWith a built-in 3-axis gravitational acceleration sensor, and unique patented algorithm