Milliard Electric Heated Germination Kit with 2.5" Tall Ventilated Dome - 16in x 10in x 3in Sealed heating coils make the heating tray more effective, extremely durable, and easier to use. Comes with humidity dome which is specially ventilated to maximize circulation of air, but minimize the release of water vapor. Perforated 28 cell seedling insert is included. Heat is thermostatically controlled to operate between 10 - 20 F above ambient room temperature to increase germination of the seeds. Input: 120V 60Hz 16W - Size: 16x10x3 inches. Dome measures 2.5 inches High.