Long-distance wireless transmission (up to 500m in open area, 10kbps air data rate). Operating frequency range: 433-458.5MHz, supports up to 255 communication channels. Maximum transmit power: 100mW (20dBm), with 10 adjustable power levels. Built-in MCU enables serial communication with external devices; transmits up to 31 bytes per packet. Supports one-to-one and one-to-many transparent transmission via ID settings. Serial port baud rate adjustment automatically synchronizes with wireless transmission rate (10kbps–100kbps). Features a three-minute startup window for AT command mode: during this period, sending 'AT+ENABLE=1' enables AT mode for parameter configuration. After this period, the module operates only in data transmission mode and AT commands are treated as standard data. Product Name: VHF/UHF Radio Modem RS485 Wireless Transceiver 20dBm 433MHz Transmitter and Receiver. Operating voltage: 4.5V–5.5V. Interface: RS485 (5V, GND, A+, B-). Frequency: 433MHz. Transmit power: -40dBm to +20dBm. Receiver sensitivity: -114dBm. Operating temperature: -25°C to +75°C. Transparent transmission baud rates: 1200, 2400, 4800, 9600 (default), 19200. Open-field transmission distance: up to 500 meters. Dimensions (without antenna): 74 x 24 x 16mm. Recommended for use with two or more units. For two units: Module 1 and Module 2 communicate bidirectionally. For three or more units: one master and multiple slaves operate similarly to a wired RS485 bus. The master transmits and all slaves receive; any slave can transmit, and the master and other slaves receive. Only one device (master or slave) may transmit at a time. Applications: IP PTZ cameras, Modbus devices, temperature sensors, LED controllers, RS485 relays, remote control systems, remote measurement systems, wireless metering, home automation, smart homes, access control, smart meters. Color: Blue. Material: Plastic and metal. Package Contents: 2 x 433M-458M VHF/UHF Radio Modem RS485 Transceiver (with enclosure). Package includes only the items listed. Note: Lighting and display differences may cause slight color variations. Measurement error allowance: +/- 1-3cm.