IMPORTANT! 1.This headphone receiver is compatible with all SIMOLIO 2.4GHz wireless tv headphones models, including SM-823 Pro, SM-823D Pro, SM-824D1, SM-824D2, SM-825D, SM-825D Pro, SM-826D, SM-8245, SM-828D1, SM-828D2, SM-829D1, SM-829D2, and SIMOLIO wireless TV speakers model SM-621D, SM-621 etc. 2. Please charge the headphone by provided USB power cable. 3. Not Bluetooth. Please use it with SIMOLIO 2.4G wireless TV headphone & transmitter system. BALANCE - Left / Right Ear Adjustment The BALANCE control is specially designed for people with different hearing levels of the left and right ears. They can adjust the balance control as needed to best fit their listening requirements. MIC - Personal Sound Amplifier Function The personal sound amplifier function is designed as an additional & unique feature to help people temporarily hear what people are talking to him when watching TV without taking off the headphones. Adjustable and Comfortable Designed with super soft earmuffs and an easily 12-levels adjustable headband providing a comfortable, customized fit. An ideal choice for extended periods of watching TV. Audio Sharing Function Designed with 3.5mm AUX share port on the right side of the headphone allows any brand of wired headphones to connect with, let you share movies/music with your friends or families without disturbing others. BALANCE - Left / Right Ear Adjustment MIC - Personal Sound Amplifier Function Adjustable and Comfortable Audio Sharing Function