Long-distance wireless transmission (up to 500m in open area, 10kbps air rate). Operating frequency range: 433-458.5MHz, supports up to 255 communication channels. Maximum transmit power: 100mW (20dBm), with 10 adjustable power levels. Built-in MCU, communicates with external devices via serial port, sends up to 31 bytes at a time. Supports one-to-one and one-to-many transparent transmission through ID settings. Changing the serial port baud rate automatically adjusts the wireless data transmission rate (10kbps–100kbps). Features a three-minute configuration window after power-on: during this time, sending 'AT+ENABLE=1' enables AT mode for parameter setup. After three minutes, AT mode is no longer accessible and all data, including 'AT+ENABLE=1', is transmitted as regular data. Product Name: VHF/UHF Radio Modem RS485 Wireless Transceiver 20dBm 433MHz Transmitter and Receiver. Operating voltage: 4.5V–5.5V. Interface: RS485 (5V GND A+ B-). Frequency: 433MHz. Transmit power: -40 to +20dBm. Receiver sensitivity: -114dBm. Operating temperature: -25°C to +75°C. Transparent transmission baud rates: 1200, 2400, 4800, 9600 (default), 19200. Open-field transmission distance: up to 500m. Dimensions (without antenna): 74 x 24 x 16mm. Recommended for use with two or more units: With two modules, each can send data to the other. With three or more, one acts as master and others as slaves, operating similarly to a wired RS485 bus. The master transmits and all slaves receive; any slave can transmit and the master plus other slaves receive. Only one device (master or slave) can transmit at a time. Applications: IP PTZ Camera, Modbus temperature sensors, LED controllers, RS485 relays, remote control and measurement systems, wireless metering, home automation, smart homes, access control, smart meters. Color: Blue. Material: Plastic + Metal. Package Contents: 2 x 433M-458M VHF/UHF Radio Modem RS485 Transceiver (with shell). Note: Light and display differences may cause slight color variations. Measurement error allowance: ±1–3cm.