Cavity back

A Cavity back golf club refers to a specific kind of iron. In a cavity-back iron, most of the weight of the clubhead is distributed around the perimeter of the head, creating a "cavity" in the center of the clubhead. This perimeter weighting increases the moment of inertia of the clubhead which minimizes twisting when the ball is struck slightly off the center of the clubhead, allowing such shots to have more distance and control than a similarly off-center shot with a traditional muscle-back "blade" iron. Such improved forgiveness is often mislabelled as providing a larger sweet spot, or center of gravity, but technically this is false as there is still an optimum point on the clubhead with which to contact the ball for best distance and straightest flight. Most golfers using a cavity back iron, however, will see no practical difference between a shot hit "dead-on" and one hit slightly off-center (where a marked difference would be seen with a muscleback), and will use the term to describe the increased usable area of the hitting face.