Completely enclosed for maximum strength, insulation, and solar heat collection. The Harvester provides the best of both worlds: a double-tiered bench frame maximizes your growing area on one side and a single bench frame on the other side is ideal for taller plants and provides easy-access workspace. All Harvester Greenhouses come with a large, louvered air vent and are covered with advanced double-walled Solexx paneling. The Harvester, like all Solexx greenhouses, is freestanding and requires no special foundation or site preparation - just level the ground beneath it.