XT-XINTE HC-05 Bluetooth Serial Adapter Bluetooth to RS232 Serial Bluetooth Communication Module Expansion Board quantity: 1pcs HC-05 Bluetooth Serial Adapter Bluetooth to RS232 Serial Bluetooth Communication Module Expansion Board Many finished products are transferred from the Bluetooth mode , this BLK-MD-BC04-B_DEMO not just transferred from the Bluetooth mode, you can always toggle button to switch from the main mode, and there is an address code below Clear key