With the zippered roll-up door and 2 Velcro side windows, you can now regulate external airflow to keep your plants warm and provide better air circulation. It also works as observation window that makes it super easy to peek inside! The Keep Warm Sunroom For Hydroponic has been constructed with 6 wired shelves (3 on each side, and measures 56.3” (L) x 28.7”(W) x 76.8”(H)) helping to make space for all your blooming flowers, sprouting plants and fresh vegetables. It features rock-solid stability as it has been structured with heavy-duty rust-resistant tubes for extended durability and is supported with an 18 lb. weight capacity making it strong enough to hold seed trays, pots and plant growth light.