1. Long-distance wireless transmission (up to 500 meters in open area , 10kbps baud rate in the ). 2. Operating frequency range ( 433 - 458.5MHz , up to 255 communication channels). Maximum 100mW ( 20dBm ) transmit ( 10 levels of can be set ). 3. -in MCU, 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 . ( 10kbps-100kbps) 5. Set the ''critical three minutes''. The module can send and receive data normally within three minutes of -on. You can send the AT '' AT+ENABLE=1 '' to make the module enter the AT 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 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 : -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 (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 as wired RS485 bus. Masterdevice transmit data, Slave devices all receive data.Any slave device transmit data, master device and the other slave devices can receive .When ever only allowed one device (master or slave) to transmit data. Application: IP PTZ Camera Modbus 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 Colour:blue Material:Plastic + Metal Package Contents: 2 * 433M-458M VHF/UHF Radio Modem RS485 transceiver(With shell) Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.