1. Long-distance wireless transmission (up to 500 meters in open area , 10kbps baud rate in the air ). 2. Operating frequency range ( 433 - 458.5MHz , up to 255 communication channels). Maximum 100mW ( 20dBm ) transmit power ( 10 levels of power can be set ). 3. Built-in MCU, use serial port to communicate with external devices. Send 31 bytes at a time. 4. The module can support one-to-one, one-to-many transparent transmission communication through ID setting Changing the baud rate of a different serial port will synchronously change the rate at which data is sent over the air. ( 10kbps-100kbps) 5. Set the ''critical three minutes''. The module can send and receive data normally within three minutes of power-on. You can send the AT command '' AT+ENABLE=1 '' to make the module enter the AT command state for parameter setting. There is only this reserved word in these three minutes. After more than three minutes, you will not be able to enter the AT command mode, you can only send and receive data, '' AT+ENABLE=1'' will also be sent out as data, there are no reserved words at this 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 Transmit power: -40~+20dBm; Receiver sensitivity: -114dBm; Operating temperature: -25 Celsius~+75 Celsius; Transparent transmission mode baud rate :1200 2400,4800,9600(Default),19200; Open ground Transmission distance : 500M Size(without antenna): 74 x 24 x 16mm Recommend to buy more than 2pcs!!! How to use (more than the =2pcs): 1/2PCS,Module 1 and Module 2 send data to each other. 2 more than the =3PCS,One as master device, the other as will be as slave device. the way they work as well as wired RS485 bus. Master