1. Long-distance wireless transmission (up to 500m in open area, 10kbps 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 supports one-to-one, one-to-many transparent transmission communication through ID setting. Changing the 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 state for parameter setting. This reserved word is only active within these three minutes. After more than three minutes, you will not be able to enter AT mode; you can only send and receive data. The 'AT+ENABLE=1' command will also be sent out as data, with no reserved words active 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 Transmit power: -40 to +20dBm Receiver sensitivity: -114dBm Operating temperature: -25°C to +75°C Transparent transmission mode rate: 1200, 2400, 4800, 9600 (Default), 19200 Open ground transmission distance: 500m Size (without antenna): 74 x 24 x 16mm Recommended for use with 2 or more units How to use (2 or more units): 1/2PCS: Module 1 and Module 2 send data to each other. 2 or more than 3PCS: One as master device, the others as slave devices. They operate like a wired RS485 bus. Master device transmits data, all slave devices receive data. Any slave device can transmit data, which is received by the master and other slave devices. Only one device (master or slave) is allowed to transmit data at a time. Application: IP PTZ Camera Modbus temperature sensor LED Controller RS485 Relay Remote control, remote measurement system Wireless meter Home Automation, Smart Home Access control Smart meter Color: Blue Material: Plastic + Metal Package Contents: 2 x 433M-458M VHF/UHF Radio Modem RS485 Transceiver (With shell) Only the above package content, other items not included Note: Light and different displays may cause the color of the item to appear slightly different from the real thing. Measurement allows an error of +/- 1–3cm.