The transparent polypropylene allows maximum ligharbonate t transmission while retaining heat for early seed sprouting or for protecting plants late in the season. Adjustable roof openings provide proper ventilation and easy access to your plants. They can be opened just a few inches to create a flat top surface or opened completely to allow full access to the inside. The lightweight aluminum frame and rust-resistant hardware help prevent corrosion from affecting all of the components of your cold frame greenhouse, making it last for seasons to come. It can help keep squirrels and other small animals from digging up and eating all those bulbs and shoots that you worked so hard planting. A peak height that measures over 18″ offers you plenty of space for plant preparation and growing.