The GrowIT Heavy Duty 12 x 20 Greenhouse with roll-up side vents delivers quality construction, quick and easy assembly, and best in class value. Featuring 1 5/8 in. heavy-duty all-steel frame, patent-pending ShelterLock Stabilizers, Ratchet-Tite tensioning, and the Easy Slide Cross Rail System for a stable and durable Greenhouse. The specially designed ClearView triple-layer, heat bonded RipStop translucent cover provides enhanced illumination for plant growth and protection. Roll-up side panels and half moons screen vents at each end provide optimal airflow and temperature control.