1. on-board MAX485 chip, is a tool for RS-485 communications, low-power, Slew-Rate Transceiver 2. onboard then 5.08 (mm) pitch 2P terminal for easy wiring RS-485 communication 3. the chip has drawn all of the pins can be controlled by the microcontroller operation 4. Working voltage: 5V 5. board size: 44 (mm) x14 (mm)