With USB serial port and Master bluetooth module HC06 can receive and transmit data from master Bluetooth module by operating USB serial port; Only matches with HC06 slave modules can't do with computer or cell phone; With indicator lights: RXTX BT( the bluetooth status indicator) D3 (the USB serial port ready indicator); The bluetooth status indicator light (BT): slow flash: already matched but temporarily not connected with any slave module Steady on: already connected with the slave module quick flash: searches link to the slave module; Set button to refine your search; Directly via USB serial port to transmit AT command of setting parameters. A product for Arduino that works with official Arduino boards.