Dew Heater - 4 Inch Objective Telescopes - SKU# AZ-704. Dew heater specs: 15" in length, 10.56 Watts @ 12 Volts, 0.88 Amps. This product requires the use of a simple D/C adapter (AZ-719) or dual channel controller (AZ-720) to be powered. Use of a dew controller other than Astrozap brand can cause damage and void the warranty.