If you photograph time lapses, star trails, or do any other type of photography that exposes your lens to the night air for more than a few minutes, you have to be careful about dew forming on the lens. Once dew starts to form, you can pretty much pack in in for the night. The LensMuff is designed to solve this problem. It works by providing a fast and secure attachment for ordinary hand warmers to wrap around your lens. Hand warmers provide enough warmth to keep the temperature of the front element from dropping to the dew point, so dew won't form in the first place. Very compact—the size and weight of an empty billfold (heavier with warmers inserted). Attaches and removes in seconds. Perfectly secure on the lens. Guaranteed to last a lifetime. Special design and materials hold heat against lens, limiting dissipation into to the air. Outer material made of tough weather-resistant pack cloth for optimal durability. Will not scratch or harm the lens in any manner. Accommodates one, two, or three hand warmers at a time. Any brand or type of standard-size chemical hand warmer packs will fit. Works equally well on spotting scopes, telescopes, and eyepieces. Design allows you to daisy chain them for use on large-diameter lenses. Full instructions included. Stylish design looks good on any lens. (A benefit if your lenses are vain!). Very reasonably priced. All brands and types of standard hand warmer packs will work in the LensMuff, but they are not included and must be purchased separately.