Honbay Wireless Bluetooth Host Serial Transceiver Module Slave and Master RS232 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 GPS receiver Industrial control MCU projects Running in slave role: Pair with BT dongle and master module Coupled Mode: Two modules will establish communication automatically when powered. PC hosted mode: Pair the module with bluetooth dongle directly as virtual serial. Default serail port setting : 9600 1 Pairing code : 1234,The core module size : 28 mm x 15 mm x 2.35 mm