This is a development board for NXP KW41Z with an onboard 3-24 V input voltage regulator, PCB trace antenna, and JTAG/SWD header. The form factor and pinout match that of an Arduino-pro-mini.
The MKW41Z512VHT4 has a Cortex-M0+ with 512KB flash, 128KB ram, and a dual-mac 2.4GHz transceiver that supports 802.15.4 and BLE.
On the rear side is a footprint to add SMTU2032-LF for CR2032 battery operation. The battery life can be up to several years if you don't need to send more than a few bytes of data per second.