Mizuno describes it as a "rolled leading edge, cambered mid-sole, and rolled trailing edge deliver consistent striking ability from all types of lies." Non-marketing lingo, the MP-57 irons performed just fine from pretty much any lie you will find on the golf course.
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 produce a slightly higher ball flight in the long irons, and a mid trajectory in the scoring irons. They also deliver the solid feel and shot making ability that the MP iron player craves. Most importantly, the MP-57′s achieve all these playing aspects, yet in a classic head profile that appeals to better players. Using the Grain Flow Forging and the Cut Muscle technologies seen in the rest of the MP line, the MP-57 are the first iron in the series to feature a full cavity. By incorporating a full cavity, the Mizuno engineers were able to make a much larger sweet spot for added forgiveness for those of us who don't make a nearly perfect swing every time.
I purchased the Irons because I love the Mizuno MP-57 design and shot making capability. And according to the description and photography presented they appeared to be nearly new.