Professional quality heat mats in home garden size! Kwik Grow 1 tray seed heaters are safe, low-voltage, and professional quality. They are designed to generate exceptionally uniform, gentle heat that is ideal for germinating seeds. Many other home garden heat mats contain wire coils, so the mats have hot and cool spots. In contrast, Kwik Grow mats distribute heat evenly over the mat and generate warmth continuously. Heaters can stay on safely, and seed trays can be placed directly on the surface of the heat mat. Insulation can be placed under the heaters to maximize energy efficiency, but this is not necessary. Soil temperatures should be monitored with a soil thermometer. If a lower temperature is required, the seed tray can be raised slightly above the heater using thin shims. Mat measures 12" x 21" and holds one standard tray. Mats are equipped with ACLI plugs as an extra safety feature!