RedBearLab BLE Mini Texas Instruments CC2540 2.4 GHz Bluetooth System-on-Chip (SoC) Certified Bluetooth Low Energy 4.0 Module with on-board chip antenna Bluetooth 4.0 Low Energy (BLE) Dimension- 39mm x 18.5mm Powering options - 3.4V to 11V VIN / 5V USB / Coin Cell Battery / 3.7V Li-ion Battery