This wireless pager system operates via RF technology. The watch receiver features an IPX7 waterproof rating, while the transmitter buttons are rated IPX4. The system operates at 433.92MHz with high sensitivity. It supports four separate call channels. It is powered by a rechargeable, high-capacity battery for extended standby time and low power consumption. Suitable for restaurants, hotels, hospitals, and care facilities. Specification: Item Type: Wireless Pager System Material: ABS Watch Receiver Parameters: Operating Frequency: 433.92MHz Charging Voltage: DC5V Battery Type: 300mAh Lithium Battery (included) Operating Current: 10020mA (Vibration and Buzzer Mode), 7510mA (Vibration Mode) Standby Current: 105mA Receiving Sensitivity: -1072dBm Decoding: Learning Code Waterproof Rating: IPX7 Operating Temperature: -20°C to 60°C Pushbutton Transmitter Parameters: Operating Frequency: 433.92MHz Size: Approx. 60x60x13mm / 2.4x2.4x0.5in Battery Type: 2 x 240mAh CR2032 Batteries (included) Transmit Current: 103mA Standby Current: <1uA Open Distance: >100 Meters Keystroke Life: 1 Million Times Waterproof Grade: IPX4 Operating Temperature: -20°C to 55°C Single Key Function: CALL Package List: 1 x Receiver 4 x Transmitter 1 x Charging Cable 1 x Instruction Manual