The Big Bertha Fusion Heavy Driver features all the same design benefits as the standard model, however, the stock length of the driver is 1 shorter 44.5. The shorter length offers increased control for those players seeking more auracy. To ensure the weighting of the driver is correct at the shorter length, a heavier 12g weight is in the rear of the head. A Material Change In Forgiveness And Distance. The Big Bertha Fusion Driver is a material change in forgiveness and distance, led by our revolutionary titanium ExoCage and ultralight triaxial carbon crown, with a new and innovative shape, and industryleading aerodynamics.