Mizuno Golf MP-54 Club Iron Sets Step Muscle Design creates additional thickness behind impact for solid feel Grain Flow Forged from a single 1025E Pure Select mild carbon steel billet Milled Pocket Cavity (3-7 irons) for off-center stability, higher launch, and steep landing angle Solid Muscle Design (8-PW) for enhanced feel and maneuverability Perimeter Grind reduces topline appearance and sole width