This part is a kind of semiconductor called NRF51822.

Function of this product has Multiprotocol Bluetooth 4.0 low energy/2.4 GHz RF SoC Product Specification.

Manufacturers : Nordic

Image and pinout :

Some of the text within the PDF file :

nRF51822 Multiprotocol Bluetooth® low energy/2.4 GHz RF System on Chip Product Specification v3.1 Key Features Applications • 2.4 GHz transceiver • -93 dBm sensitivity in Bluetooth® low energy mode • 250 kbps, 1 Mbps, 2 Mbps supported data rates • TX Power -20 to +4 dBm in 4 dB steps • TX Power -30 dBm Whisper mode • 13 mA peak RX, 10.5 mA peak TX (0 dBm) • 9.7 mA peak RX, 8 mA peak TX (0 dBm) with DC/DC • RSSI (1 dB resolution) • ARM® Cortex™-M0 32 bit processor • 275 μA/MHz running from flash memory • 150 μA/MHz running from RAM • Serial Wire Debug (SWD) • S100 series SoftDevice ready • Memory • 256 kB or 128 kB embedded flash program memory • 16 kB or 32 kB RAM • On-air compatibility with nRF24L series • Flexible Power Management • Supply [ ... ]

NRF51822 PDF Datasheet Download