DSD TECH HC-06 Wireless Bluetooth Serial Transceiver Support Module Slave and Master Mode For Arduino + 4PIN DuPont Cable Industrial serial port bluetooth, Drop-in replacement for wired serial connections, transparent usage. You can use it simply for a serial port replacement to establish connection between MCU and GPS, PC to your embedded project and etc. Computer and peripheral devices Running in slave role: Pair with BT dongle and master module Allows your device to both send or receive the TTL data via Bluetooth technology without connecting a serial cable to your computer. Default serail port setting : 9600 1 Pairing code : 1234 Module working voltage 3.3V to 6V