VocoPro SingAndHear-Solo - All-In-One Wireless Microphone/ Wireless In-Ear Receiver System Built-in rechargeable battery with 6 hours of run time on each charge. (3. 7V Li-ion 650 mAh) Extend run-time with mini 5V USB charging port or power bank (not included) as power source Tap-and-sync (TM) allows users to change frequency and automatically re-connect at the tap of a button Digital UHF Operates in 900 MHz, away from TV, Radio and Wi-Fi interference