HC05 Bluetooth Master-Slave Module for Arduino, Bluetooth module SPP (Serial Port Protocol) module, designed for wireless serial connection setup. It has EDR (Enhanced Data Rate) of 3Mbps Modulation with complete 2.4GHz radio transceiver and baseband.
It uses CSR Bluecore 04-External single chip Bluetooth system with CMOS technology and with AFH(Adaptive Frequency Hopping Feature).

Hardware Features:
Typical -80dBm sensitivity 
Up to +4dBm RF transmit power 
UART interface with programmable baud rate
Master-Slave 6-Pin anti-reverse
Integrated Antenna

Software Features:

Default Baud rate: 9600/38400, Data bits:8, Stop bit:1, Parity : No parity, Data control, Supported baud rate:600,19200,38400,57600115200,230400,460800. 
Auto-connect to the last device on power as default. 
Permit pairing device to connect as default.  
Auto-pairing PINCODE:”1234” as default