The new HC2A-AW comes with new and enhanced electronics, which improves the self-heating property compaired to its predecessor HC2-AW. The HC2A-AW has the Rotronic UART Connector and can be used with the HygroLab. The HC2A-AW-USB Probe has an USB Connector for direct connection to a PC in combination with the HygroSoft Software. The HygroSoft Software with the Water Activity function must be ordered separately.