Main features:*Hands-Free Headset:This headset is a real hands-free Bluetooth headset solution that allows you to really releaseyour hands while driving, working, exercising and it's extremely convenient.*Perfect companion for Business Headset：The headset is the perfect companion for Business Headset, with two different sizes of silicone earplugs,deep sleep power saving mode, using CVC6.0 noise reduction technology to ensure that thecall in a noisy environment, clear quality；Equipped with mute button,support mute the mic if you don't want other side person hear you.*Simple and convenient:180 degree rotatable ear hook can be used for the left and right ears, you can find a moreTechnical Parameters*Bluetooth Specification: V4.1+EDR*Transmission distance: 33ft (10m)*Noise Reduction: CVC 6.0*Working voltage: 3.7V*Charging voltage: DC5V*Charging Time: about 2.5 hours*Talking time: about 32 hours*Music time: about 24 hours(80% volume)*Standby time:about 720 hours*Frequency response: 20 - 22kHzNOTE:For safety reasons,it is recommended not to use the headset while it is charging 2.If the output of your charger for your headset is over 5V,it will damage your headset potentially.It is recommended to use standard charger for your headsetPackaging Information:1*K21 Headset