https://www.silabs.com/development-tools/wireless/efr32xg28-explorer-kit?tab=techdocs
xG28-EK2705A - EFR32xG28 Explorer Kit - Silicon Labs
The EFR32xG28 (xG28) Explorer Kit is a small form factor dev kit for rapid prototyping of IoT applications using sub-GHz and BLE wireless protocols.
explorerkitsiliconlabs