* Warms root area approximately 10° - 20° F over ambient temperature to improve germination process. * Helps gardeners have better success rates with seedlings & cuttings. * Perfect for one standard 10" x 20" propagation tray. * Heavy-duty construction makes this mat very durable. * More than 20% larger than competitive mats. This allows even warming of your entire tray. * More consistent heating with fewer hot spots than other seedling heat mats. * Ed Hume seal of approval. * Dimensions: 21" x 10" * 20 watts