The TELRAD dew cap prevents the projection screen from fogging up in unfavourable weather conditions. With built-in 90° deflecting mirror for easier use in zenith position. The functionality is quite simple. If the TELRAD viewfinder is not used in the meantime, simply flip the dew cap over the viewfinder projection screen. This saves the annoying wiping off of the humidity and the viewfinder is always ready for use. The dew cap is made of impact-resistant plastic and additionally protects the viewfinder projection screen from scratches during transport. The retrofitting of the dew cap is very easy and is done by the two screws on the side.