This is the breakout board of RF transceiver module BCM-3601-X02. It has a spring antenna and breaks out the module pins for easy connection with external host MCU.
The BC3601 is a bidirectional FSK / GFSK high performance RF transceiver IC from Holtek that operates in the license-free 315MHz, 433MHz, 470MHz, 868MHz, and 915MHz ISM (Industrial, Scientific and Medical) bands.
The BCM-3601-X02 is a BC3601 based FSK RF transceiver module operating at 433MHz. It communicates with the host MCU via SPI interface.