The Mizuno Pro 243 is a manufacturing masterpiece – more compact and precise than its predecessor, yet faster from the face and more satisfying at impact.  Improvements in performance only made possible through the long-term relationship between Mizuno's R&D team and its exclusive Grain Flow Forging plant in Hiroshima, Japan. Grain Flow Forged HD: One-piece Grain Flow Forged HD from 1025E Pure Select mile carbon steel at Mizuno's iconic facility in Hiroshima, Japan. Where Mizuno irons have been produced since 1968. Harmonic Impact Technology: Fine tuned head geometry delivers ideal impact feel and feedback Copper Underlay: Thin copper layer beneath a nickel chrome to provide a further enhanced impact feel Grain Flow Forged Chromoly: Our strongest Forged material with the solid, soft consistent feel of Grain Flow Forged Micro Slot Technology: Milling the head from the sole up creates a Micro-slot that activates the strength of the 1025 Boron material for added distance and increased forgiveness 4120 Chromoly with Flow Microslot: Featured in the 4-7 irons, a wider, longer micro-slot to create a more expansive high energy area in each club face.  Resulting in a higher flight and faster ball speeds. 1025E Pure Select Mild Carbon Steel 8-GW: Solid feel and control where most wanted, with modern lofts to maintain even distance gapping through the set. Wrap-Around Sole Grind: Heavy relief around the sole for improved turf interaction and seamless transition from micro-slot 7 iron into traditional 8 iron construction. Compact Player's Profile: Dramatically reduced topline and blade length throughout the set. Increased Bounce: Another direct request from the tour.  Increased by a degree in the long irons and 2 degrees in the scoring irons for improved turf interaction. Satin Nickel Chrome Finish : An elegant, yet durable, non-glare finish.