1、Multifunction: Mobile phone handset can be used to answer a call hang up a call, reject a call, redial, power off, etc. The volume can be adjusted. 2、3.5mm and USB C: Suitable for all devices with audio jacks or USB C connectors (included).(for Opis Lightning adapter is required for iPhone 7/7+ and later) 3、Radiation Proof: Just plug in the device and use it, this handset can reduce radiation, and with a 1M/3.28FT extension cable, you can easily answer calls. 4、Excellent Audio Quality: Built in HD speaker and microphone old fashioned high volume handset style and excellent microphone make calls fun! 5、Easy to Use: Not a Bluetooth phone and no pairing is required. It's just a simple plug and phone connection. Your phone will automatically use the handset! Make vour phonel retro!