Astrozap Dew Heater - 11 Inch Objective Telescopes - SKU# AZ-711. 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: 39" in length, 30.36 Watts @ 12 Volts, 2.53 Amps.