Unique, "Living Hinge" Design Allows Hands-Free Drive In/Drive Out- No Need To Manually Raise Or Lower The Endwalls. Entry and exit walls are supported every 12" with a patented "living hinge". Once a vehicle has entered or exited, the walls automatically spring back to their vertical position. Both long sidewalls are held upright by PVC sidewall assemblies. Simply swivel the feet to lower the sidewalls for storage or transport to another location.