No set-up required - unfold and the sidewalls automatically spring into their vertical position. Rugged Construction - made of XR5, a polymer-coated fabric; offers excellent chemical resistance and durability. Polyurethane and other materials also available. Vertical sidewall supports located every 12". Each Support features a built-in "living hinge" at its base, which allows sidewalls to collapse in either direction. Collapsed sidewalls spring back automatically.