We are extremely impressed by how well this mini-greenhouse is designed to increase germination success by providing gentle warmth to the planting bed and by controlling humidity. The exceptionally tall dome, a full 6-1/2" high, is excellent for taller starts and cuttings. Two ventilation points at the top of the dome give you better humidity control to foster optimum growth. The complete kit includes everything you need: a UL-listed waterproof heat mat that maintains an ideal temperature range for seed germination, clear dome with dual vent points, 11" x 22" watertight base tray and 72-cell seedling insert. Instructions included.