1STABLE SIGNAL AND ANTI INTERFERENCE: Stable signal with 1000m long distance transmission; Provides enhanced antiinterference function for the patented pairing technology. 2RECHARGEABLE AND PORTABLE: Equipped with a 500mA lithium battery and a low battery indicator, the CALL button can be fully charged in about 3 hours, with a charge time of up to 30 days. The receiver can be fully charged in approximately 3 hours and remain charged for up to 7 days. 3CALLER ID AND EASY TO EXPAND: The receiver has a caller ID function that tells you who is seeking help; the system can be expanded for more receivers and more call buttons. 4VOLUME AND TONALITY ADJUSTABLE: There are 4 volume levels and 12 tonality available; in addition, the CALL button has a night light for better use. 5USE ADVICE: If you encounter any product installation test abnormality, please do troubleshooting first. Equipped with a lanyard and belt clip for easy carrying Item Type:WirelessCaregiverPagerCallButton Material: ABS Transmitter Built In Battery: Lithium Battery 500mah Receiver Built In Battery: Lithium 500mah Frequency Range: 433MHz Receiving Sensitivity: -120dBm Operating Temperature: -25~65 Degrees Celsius Power Failure Memory Function: Support Number of Connections: 1 To 8 1 x Transmitter 1 x Receiver 1 x Charging Cable 2 x Shoulder Strap