Astrozap Dew Heater - 9 & 10 Inch Objective Telescopes - SKU# AZ-709-710. 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. Dew heater specs: 37" in length, 20.16 Watts @ 12 Volts, 1.68 Amps.