The 21' and 30' wide Atlas RT™ Gutter Connect uses an all rectangular tube frame that offers incredible strength, versatility and labor saving construction. They are an excellent choice if you choose to use natural ventilation. With gutter heights from 8' to 12' you can get the height you need and still save money. Our 21' wide features a rounded roof design and an exrtuded aluminum gutter that has double bolt track extruded on each side for easy attachment of bows and poly fasteners extruded inside the gutter to eleminate screws and bolts that are usually required to attach lock. Our 30' wide has an arched style roof design that offers an 8' rise from the truss to the peak, thus providing cooler tempratures from floor to truss and with sidewall heights from 8' to 12' provides more room for tall plants and vegetables. This structure also uses the same extruded aluminum gutter described for our 21' wide structure. Our RT™ Gutter Connect is the perfect solution if you need higher sidewalls and side curtains. Ships in 5 days.