1. Long-distance wireless transmission (open field 1200m / FU4 mode, air baud rate 1000bps) 2. Operating frequency range (433-458.5MHz, up to 255 communication channels) 3. Maximum 100mW (20dBm) transmit power (8 levels of power can be set) 4. Four working modes to adapt to different applications 5. Built-in MCU, communicate with external devices through serial port The number of bytes sent at one time is up to 256 bytes The module supports one-to-one, one-to-many, many-to-many connection transparent transmission Parameter: Chip: SI4438 Working frequency band: 433 ~ 458.5MHz Communication interface: UART 3.3V / 5V TTL level Antenna interface: spring antenna / antenna socket Working voltage: 3.2 ~ 5.5V Sleep current: no sleep mode Communication level: 3.3V / 5V level Working humidity: 10% ~ 90% Transmit power: 20dBm (MAX) Working temperature: -25 Celsius ~ + 75 Celsius Reference distance: 1200m Storage temperature: -40 Celsius ~ + 85 Celsius Colour:black Material: PCB Size:26 x 12 x 6mm Package Contents: 1 x wireless single chip module Only the above package content, other products are not included. Note: Light 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.