The Testo 875i-2 Thermal Imager Kit features a 32° x 23° high-quality, standard lens and a temperature sensitivity of 50mK. The NETD indicates the smallest possible temperature difference that can be resolved by the imager. The Testo 875i-1 thermal imager has a temperature measurement range up to 622°F, refresh rate of 33 Hz, and manual focus. The 875i-1 provides a large 3.5" LCD screen and an accuracy of ±2% of the reading.