Overhead Door™ Rolling Steel Storm Shelter Doors start with the features of our Model 610 with reinforcements for additional safety. These doors feature 12-gauge curved slats that provide a natural water-shed, helping to reduce corrosion. The curved slats are designed with free-acting interlocking joints that permit easy articulation when the door coils. They feature a powerful double-angle bottom bar designed to reinforce the structural integrity of the door and help prevent unwanted entry. A spring barrel encases the counterbalance mechanism and provides the axis around which the curtain coils. These doors come standard with an Overhead Door® RSX® Fire Door operator, built with a fuse link mechanism for drop on alarm and integration into a single push button activation system.