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; humidity controlled Super Sprouter® 7 in Propagation Dome with vents. The Seedling Heat Mat is ETL listed.