Keeps the dew off. - Celestron Telescopes Lens Shades

As suggested in another review getting the fit and alignment on your scope can take a bit of futzing to get the cylinder aligned with the optical axis. I did not find that a reason to ding the shade down from 5 stars because I only had to adjust the circumference once.

The cylinder is held together with Velcro. After a few openings and closings I was able to slide the lens shade on with just the right snugness. I store the lens shade in its cylindrical configuration.

Now to what's really important. Both the local park where I set up as well as the remote site I go to for darkish skies tend to be humid. Before getting this accessory I was lucky to get 90 minutes of observing before having to shut down due to fogging. Since getting the lens shade I have not had the corrector plate fog up despite dew forming on numerous local surfaces.