Consisting of two high visibility yellow security chains made of powder-coated steel, the Dual Chain is anchored in aluminum rings from opposite sides of the loading dock door frame. The chains are then stretched across the loading dock and secured into their corresponding receivers by pre-attached turnbuckles. This product is manually operated and comes in lengths that accommodate door sizes of 8-10 feet.
http://apsresource.com
http://apsresource.com