"Heating strips - keeping your view of the night sky clear Nights are not always as dry and clear as you would like. Optical surfaces will often fog up at night. And once your optics - eyepieces, lenses or Schmidt corrector plates - have fogged up, then your observing is over for the night. But this can be avoided. Tydeux heating strips keep off the dew and guarantee you super clear observing - all night long. The advantages in a nutshell heating strips stop your telescope, finder and eyepieces from fogging up. easy adjustment - a flexible strip for a perfect fit available in different lengths Compact and can be used at any time Highly practical - at the beginning of your observing session, simply wrap the heating strip around the OTA or your eyepiece. The strip fits like a glove and can be fixed in place using the adhesive strap fastener. After you are finished observing, just stow it back in the eyepiece case. Your telescope heater ensures that your optics are free of fog and that you have a clear view, so it is always convenient. Keep your optics from fogging-up A 12V DC supply evenly distributes the energy to the strip at just 0.2 Watts per centimetre. The heating strip effectively keeps the temperature just a few degrees above the ambient temperature, just enough to ensure that dew no longer has a chance to form. It also uses minimal energy, hence sparing your battery. Why do your optics fog-up? The effect of dew on an optical surface is well known to every spectacle wearer who has come into a warm room from cold conditions outside - a fine mist of water droplets forms on the spectacles as the warm air condenses onto the cold glass surfaces. Exactly the same happens on the lenses of your telescope optics. As your optics cool down, water condenses onto the surface. Then it's time to free your view!