he Core module is HC-05 bluetooth 2.0 module.
By using this Bluetooth module, you can quickly add Bluetooth features to your for arduino project.
The factory setting is slave mode, but you can set this module to master mode so that you might be able to connect to other Bluetooth 2.0 devices.
Please note: This is a classic Bluetooth 2.0 module, it is not compatible with iphone or ipad If you need to use to control your for arduino project. You may need a Bluetooth 4.0 ble module (such as SH-HC-08 Bluetooth 4.0 ble module)