The Bluetooth Shield integrates a Serial Bluetooth module. It can be easily used with Arduino /Crowduino for transparent wireless serial communication. You can choose two pins from Arduino D0 to D7 as Software Serial Ports to communicate with Bluetooth Shield (D0 and D1 is Hardware Serial Port). It also expand five analog IOs that you can use it to connect other devices. The Bluetooth Shield could be setting to Master or Slave by user.
Serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR(Enhanced Data Rate) 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).
Only between master device and slave device can be paired with each other. Between Master and Master devices or Slave and Slave devices can't be paired each other. The Slave mode could be paired with PDA, PC etc.