This Siemens Building Technology QFA3171 is an excellent outside air RH/Temp sensor that is suitable for various HVAC and refrigeration applications. The sensor is designed to provide accurate and reliable measurements of temperature and relative humidity, making it an essential tool for maintaining optimal conditions in your HVAC system. With its robust construction and high-quality materials, this QFA3171 model is built to last and withstand harsh environmental conditions. The sensor is easy to install and requires minimal maintenance, ensuring hassle-free operation. Whether you're looking to upgrade your existing HVAC system or need a reliable sensor for a new installation, this Siemens Building Technology QFA3171 is an excellent choice.