Cavity Back Nine-Iron
This is the nine-iron used by the majority of golfers. The cavity back club scoops out much of the excess weight in the club and distributes it through the primary hitting areas on the face of the club. This is ideal for all beginners and high-handicap golfers. It is also excellent for upper-echelon golfers who don't want to use a club that carries excess weight.
Muscle Back Nine-Iron
This club is for low-handicap players and others who consider themselves versatile shot makers. While the cavity back club may be lighter than the muscle back, the muscle back can be used with greater ease if the golfer wants to chip with his nine-iron and not just pitch. By closing the angle on the nine-iron, a golfer can play a bump and run from anywhere up to 70 yards and put it on the green.
At the Driving Range
Try out both the cavity back and the muscle back at the driving range. They should have several to choose from and you can determine which one you like better. You do not have to go on an expert's recommendation. By trying it at the driving range, you can make your own determination on which club is best for your game.