This module comes soldered on a base board with 3.3V regulator on board, module can be powered by 3.6V - 6V supply. RXD TXD pins are 3.3V level so connect MAX3232 for connecting it with PC serial port. Onboard LED is for status. Default Pairing password is 1234. for AT command and other information refer to HC-05 datasheet. On board reset key for hardware reset of the device.