Working voltage: 4.5V-5.5V;Interface : RS485 Frequency: 868MHz Transmit power: -40~+20dBm;Receiver sensitivity: -114dBm;Operating temperature: -25~+75;Transparent transmission mode baud rate :1200 2400,4800,9600(Default),19200;AT mode configured baud rate fix is: 9600BPS; Open ground Transmission distance : 500M; Size(without antenna): 58.5x30x13.8mm; Weight(without antenna):16.8g How to use ( equal 2pcs): 1: 2PCS,Module 1 and Module 2 send data to each other. 2: 3PCS,Module 1 sends data, module 2 acts as a repeater (multiple repeaters can be used), and module 3 receives data; delay sending and receiving distance. 3: equal 3PCS,One as master device, the other as will be as slave device. the way they work as well as wired RS485 bus. Master device 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 PTZ Camera Modbus modbus temperature sensor LED Controller RS485 Relay Remote control, remote measurement system; Wireless meter ; Smart Home,Home Automation ,Wiser Home; Access control ; Identification system ; Data collection; IT household appliance ; Intelligence household appliance; Baby monitoring system; 868M Sucker Antenna: Applicable Frequency : 868MHz/915MHz Gain: 5.0 dBi S.W.R. Less than 1.5; Input Impedance: 50ohm Antenna Length : 110mm Cable Type : RG174 Connector Type : SMA plug straight Cable Length : 1M Colour:green Material:PCB+Plastic+Metal Package Contents: 1 x Multifunctional wireless RS485 transceiver 1 x Antenna Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.