RF type is Transceiver; 802.11 b/g/n (Wi-Fi, WiFi, WLAN) from the Evaluation board.As you can see, this RF Board comes from the well-known Wizard Gecko series of products.
SLWRB4321A Features
Transceiver; 802.11 b/g/n (Wi-Fi, WiFi, WLAN) Type
SLWRB4321A Applications
There are a lot of Silicon Labs SLWRB4321A RF Boards applications.