Enhanced Ultrasonic Frequency - Plug Seedling heat mat is perfect for vegetable, herb, and flower seedlings Warms roots and soil an extra 10-20 degrees to optimize conditions for growing during colder months or in indoor gardening applications. Evaporation of water from the soil gently humidifies budding leaves to keep them moist and turgid with frequent watering Double-insulated waterproof construction safeguards against spills or accidents, and growing guides are printed directly on the mat for quick reference Includes: Heat Pad, Power Cord, and Instructions.18W/120V. Measures 21 x 8 inches.