BLE Bluetooth 4.0 HM-10 CC2541 CC2540 Serial Wireless UART Transceiver Module HM-10 Bluetooth Descriptions: Still use Bluetooth 2.1? IF you are in need of such a 4.0 BLE Bluetooth module, MCU can be set up,also can controlled by a remote Bluetooth device for setting,can transfer data, and can remotely control 10 PIO pins,so,the best choice is HM-10/11 bluetooth module. HM-11 size is only have 2