This simple 2 watt dew heater is the best thing that ever happened to a Telrad reflex finder. The 12 volt dew heater (made by Telescope Solutions) slides into place in seconds and keeps the Telrad clear, even in the most severe conditions. It's easy on the battery too, drawing only 0.16 amps. Comes with a 6' long cord with a standard phono-type ("RCA") male connector. The Telrad dew heater plugs into your existing dew controller or can be powered by a cigarette lighter adapter (not included).