MoonLites 12 volt plastic molded dew heater just slides into place in your telrad and keep all optical surfaces clear in the most severe conditions. It draws much less current at .16 amps then the popular velcro brand stick on type that draws .8 amps. Plugs into your existing 12 volt controller or cut the plug off and wire it to your battery.
Order online at URL above. Only $21 and will save your battery power.