For 4 flats. Seeds germinate quickly and seedlings grow bigger and stronger with warm feet! Simply roll the heavy gauge vinyl mat out on any flat surface and place your seed tray directly on top of the mat. The direct contact means no heat loss. Built-in thermostat holds the soil temperature 10 to 20 degrees higher than room temperature. Plugs into a standard outlet. UL approved. Includes easy reference growing tips printed directly on the mat.