The AstroZap AZ-719 D/C Adapter was built specifically for those individuals that don't want to purchase a Dew Controller. Works great with AstroZap Dew Heaters and Flexi-Heat Dew Shields. So how does it work All you have to do is take one end of the D/C Adapter and plug it into the Cigarette Lighter / 12v DC power supply of your vehicle. Once connected a stream of power will be provided to your AstroZap dew heater or flexi-heat dew shield.