Mizuno Golf MP-57 Iron Set with Project X 5.5 Shafts: The Mizuno MP-57 irons are a crowning achievement in the evolution of Mizuno's award winning Grain Flow Forging and Cut Muscle technologies. The Product Development team undertook the task of making the MP-57's the first MP iron with a full cavity, resulting in a significantly larger sweet area than any other iron in the history of the MP line. Along with increased forgiveness, the MP-57's with Cut Muscle technology will deliver the feel and shot making ability that MP iron players crave. Most importantly, the MP-57's deliver all these playing aspects, yet in a classic head profile that appeals to the better players.