Start your growing season early with everything you need in this kit to start your seedlings. It is proven that seeds grow better with ambient temperatures 10?20? F above room temperature. The Super Sprouter? Seedling Heat Mat will provide even warm temperatures for your plant starts. The 7 in dome will give your plants more room to grow with humidity control. Kit includes Super Sprouter? Seedling Heat Mat 10 in x 21 in, 72-site seed cell tray insert, 10 in x 20 in propagation tray and humidity-controlled Super Sprouter? 7 in Propagation Dome with vents. The Seedling Heat Mat is ETL listed.