1. Long-distance wireless transmission (up to 500m in open areas, 10kbps air speed). 2. Operating frequency range (433 - 458.5 MHz, up to 255 communication channels). Maximum transmission power of 100mW (20dBm) (10 power levels adjustable). 3. Built-in MCU, use serial port for communication with external devices. Transmits 31 bytes at a time. 4. The module supports one-to-one and one-to-many transparent transmission communication via ID setting. Changing the serial port speed will synchronously change the data transmission speed over the air (10kbps-100kbps). 5. Set 'critical three minutes'. The module can send and receive data normally within three minutes of power-on. You can send AT 'AT+ENABLE=1' to enter AT mode for parameter settings. Only this reserved word is active during these three minutes. After three minutes, AT mode cannot be entered; only data transmission is possible. 'AT+ENABLE=1' will also be sent as data, with no reserved word at that time. Product Name: VHF/UHF Radio Modem RS485 Wireless Transceiver 20DBM 433mhz Transmitter and Receiver Working Voltage: 4.5V-5.5V; Interface: RS485 (5V GND A+ B-) Frequency: 433MHz Transmission Power: -40~+20dBm; Receiver Sensitivity: -114dBm; Operating Temperature: -25℃ to +75℃; Transparent Transmission Mode Speed: 1200, 2400, 4800, 9600 (Standard), 19200; Open Area Transmission Distance: 500M Size (without antenna): 74 x 24 x 16mm Recommend purchasing 2 or more! How to use (for 2+ units): 1/2PCS: Module 1 and Module 2 send data to each other. 3+PCS: One acts as the master unit, the others as slave units. They function like a wired RS485 bus. The master unit transmits data, and slave units receive it. When all slave units transmit data, the master unit and other slave units can receive. At any given time, only one unit (master or slave) can transmit data. Applications: IP PTZ Camera Modbus Temperature Sensor LED Controller R4D3C32 N4D8B08 N4D8C12 RS485 Relay Remote control, remote measurement system; Wireless meter; Home Automation, Wiser Home; Access Control; Smart Meter Color: Blue Material: Plastic + Metal Package Contents: 2 * 433M-458M VHF/UHF Radio Modem RS485 Transceiver (with shell) (Other products are not included.) Note: Light and different displays may cause the color of the item in the picture to differ slightly from the real thing. The allowed measurement error is +/- 1-3 cm.