De TFA Cosy is a compact thermometer and humidity gauge. You can view the indoor temperature and indoor humidity level on the digital color display. The weather station also has a digital hand that indicates the comfort level in your home. This is based on the humidity level (dry, comfortable, and wet). Based on this information, you'll know whether to air out or dehumidify the space. Place the weather station anywhere you want. It runs on batteries, so you'll never have to rely on cables or a power strip.