Celestron Dew Heater Ring - 8"The Celestron Dew Heater Ring is the ideal dew prevention solution for your Celestron telescope. This must have accessory will improve your observing or imaging nights year round. The Dew Heater Ring permanently mounts to your 8" Celestron Schmidt Cassegrain, EdgeHD, and RASA optical tube, replacing your retaining ring, so you'll never be caught without it. The installation process is quick and easy (follow the manual for instructions). How it works