The Mizuno Pro S-1 irons are pure muscle backs, designed for players who demand ultimate precision and workability. At the core of the Mizuno Pro S-1 is Mizuno’s Grain Flow Forged HD process, carefully executed in Hiroshima, Japan. Forged from a single billet of 1025E Pure Select Mild Carbon Steel, the S-1 delivers the unmistakably soft and responsive feel through impact that Mizuno is globally known for. The inclusion of a copper underlay further optimizes this experience, subtly refining vibration patterns to produce the purest, most satisfying feedback.