SHAREME FUNCTION: the Bluetooth headset allows 2 Zinsoko Headphones to connect to the same device to listen to the same music or audio program simultaneouslyBLUETOOTH CONNECTION: able to connect to all Bluetooth V4.1 devices; the next time you use the same device, it will be automatically connected within 2 secondsBUILT-IN MICROPHONE: allows you to have a high-quality phone call conversation; the microphone is set close to the mouth to get the voice clearer and louderLONG LASTING BATTERY LIFE: with only 2 hours of charging time, the built-in 400mAh rechargeable lithium battery can support the headset to work continously about 20 hours(18H Play Time, 20H Talk Time, 300+H Standby Time)ADJUSTABLE AND FOLDABLE: the headsets can be adjusted to fit most head size for long hours comfort; the lightweight headset is foldable for easy storage, offering great convenience for travel and transport