Advanced 12-volt DC dew prevention system powers up to four heating bands. Microprocessor-controlled circuitry delivers pulse-width modulation for stable, precise temperature control. Each heater output has its own temperature control knob with adjustment from 0 percent to 100 percent. Heating bands are power-efficient, drawing only 0.25 amps to 2.8 amps at maximum output. Don't let dew dampen your spirits - or your optics. The Dew Zapper Pro 4-Channel Control Module is part of the larger Dew Zapper Pro 4-Channel Dew Prevention System. Individual heating bands are sold separately from the control module. With Dew Zapper Pro you'll never again have to quit an observing or imaging session because dew clouded up your optics. Orion's advanced dew prevention system powers up to four individual heating bands independently. So you can keep all of your optics — main telescope, finder scope, guide scope, eyepieces, or other optical accessories — fog free in high humidity or dew-prone weather. Different heating band sizes are available to suit a variety of telescopes and accessories. The Dew Zapper Pro control module is powered by a 12-volt field battery and comes with a car lighter-style DC plug on a 12 inches cable. The microprocessor-controlled circuitry delivers pulse-width modulation for stable, precise temperature control. Each of the four heater outputs has its own temperature control knob with a full range of adjustment from 0 percent to 100 percent, and each has a red LED power indicator. Set the output of each channel to provide just the right amount of heating for the prevailing conditions. The heating bands (sold separately) are highly power efficient, drawing only 0.25 amps (for 3518) to 2.5 amps (for 3522) at maximum output. A 10-amp fuse in the control module prevents any mishaps from electrical surges or reversed polarity. And unlike competing dew-prevention systems, the Dew Zapper Pro's heating bands have right-angle cable connections to reduce cable strain and provide a tighter fit. Hook-and-loop fasteners hold the bands snugly around your instrument and accessories. Each heating band comes with a 6 inches-long cable that plugs into the control module via an RCA-type connector. Removable caps are included to protect any unused ports from exposure to the elements. The control module also has an auxiliary 12-volt port, which allows you to power any 12-volt accessory directly from the module.