Waveshare BLE4.0 Bluetooth NRF51822 Module 2.4G Wireless Communication Module Mother Board Expansion Development Board Kit for Arduino Onboard battery holder, multi power supplies are available All the IOs are accessible for easy expansion Integrates CP2102 for debugging LEDs and user keys, compatible with other official boards, easy to use designed for BLE4.0 Bluetooth 2.4G Wireless Module