This part is a kind of semiconductor called RN4020.

Function of this product has Bluetooth Low Energy Module.

Manufacturers : Microchip

Image and pinout :

Some of the text within the PDF file :

RN4020 Bluetooth® Low Energy Module Features • Fully certified Bluetooth® version 4.1 module • On-board Bluetooth Low Energy 4.1 stack • ASCII command interface API over UART • Device Firmware Upgrade (DFU) over UART or Over the Air (OTA) • Microchip Low-energy Data Profile (MLDP) for serial data applications • Remote commands over-the-air • 64 KB internal flash • Compact form factor: 11.5 x 19.5 x 2.5 mm • Castellated SMT pads for easy and reliable PCB mounting • Environmentally friendly, RoHS compliant • Certifications: FCC, IC, CE, QDID, VCCI, KCC, and NCC Operational • Single operating voltage: 1.8V to 3.6V (3.3V typical) • Temperature range: -30°C to 85°C • Low-power consumption • Simple, UART interface • Integrated Crystal, I2C Interface, Internal [ ... ]

RN4020 PDF Datasheet Download