Frozen camera desiccant
Four small desiccant tablets are used inside the sensor chamber to keep the sensor from forming dew or frost. These pellets should be replaced at the first sign of moisture on the inside of your sensor. A packet of tablets comes standard with all ZWO cooled cameras, but when you run low, you can load up on them by purchasing this packet. Scan through the attached PDF in the Files tab to see an image of the inside of the sensor chamber, and the location of the desiccant tablets, as well as basic instructions for replacement.