The full overlap box, or FOL as it is known in the industry, is the second most efficient box in the corrugated cardboard box industry. However, depending on what you pack it may rival even the RSC in design. This is because it provides extra protection on the top and bottom of the box. In many cases, this is where most of the damage occurs during transport.
With a FOL you get double wall protection in a single wall box without having to pay for a full double wall box. It also over laps the joint so there are no gaps in the box.
Use this for heavier items that are shipped by courier and/or if you want a bit more security from theft along the way.