What are cavity back irons?

Answer 1

A cavity back iron is any iron in which a small to large amount of the metal across the back of the head is removed, allowing that weight to be re-positioned on the perimeter of the head, farther away from the head's center of gravity.

A muscleback iron is the term given to any iron in which there is no cavity on the back of the head, i.e., the weight is more evenly distributed across the back of the clubhead.


All cavity back irons will have a higher moment of inertia about the vertical axis of their centers of gravity, so they twist less from an off-center hit. By twisting less from a toe impact or heel impact, the cavity back is more forgiving than the muscleback design. Therefore, off-center shots from the cavity back iron will fly a little farther than the same off-center hit with a muscleback iron design.

Here's a photo of both to help you:

http://www.ifyougolf.com/features/macgregor2002/clubs/