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. Developed and tested with input from tour professionals, the S-1 incorporates a Channel Back Design that redistributes mass for greater vertical stability and a more consistent center of gravity. This design works seamlessly with Mizuno's Harmonic Impact Technology, which fine-tunes the feel by adjusting the club's vibration frequencies to deliver even more responsive feedback. Further Optimized Grain Flow Forged HD (High Density) The S-1 iron is masterfully Grain Flow Forged HD from a single billet of 1025E Pure Select Mild Carbon Steel in Hiroshima, Japan-a testament to Mizuno's heritage in precision forging. This advanced forging process creates a tighter grain structure, delivering the brand's legendary buttery-soft feel through impact, while enhancing feedback and consistency across the set. Channel Back Design The innovative Channel Back Design subtly repositions mass behind the face to achieve a more stable vertical center of gravity, resulting in consistent launch conditions. Simultaneously, it offers a firmer, tour-preferred sensation, enhancing responsiveness without sacrificing the purity of feel. Harmonic Impact Technology (H.I.T.) Mizuno's proprietary Harmonic Impact Technology works in tandem with the channel back geometry to fine-tune vibration frequencies, delivering a slightly firmer-but still satisfyingly solid-impact sensation. It's engineered for players who desire auditory and tactile feedback that inspires confidence with every strike. Copper Underlay A thin layer of copper beneath the chrome plating, adds a layer of nuance to the feel at impact. This feature subtly softens vibration, enriching the feedback while maintaining a crisp response. Paired with H.I.T., it creates what Mizuno describes as the ultimate "sensory connection" between golfer and club. Tour-Tested and Confirmed Sole Geometry The S-1 sole has been carefully refined through tour input, featuring a flatter camber profile, sharpened leading edge, and increased bounce angle. This design ensures smoother turf interaction-particularly beneficial for shallower swings-minimizing digging and allowing players to maintain aggressive angles of attack with confidence. Soft White Satin Finish The irons are finished in a sophisticated Nickel Chrome Soft White Satin, offering a premium, tour-inspired aesthetic. Beyond its visual appeal, the satin treatment effectively reduces glare at address, promoting unwavering focus and visual clarity in all lighting conditions.