The second generation of Mizuno's staggering Hot Metal Blade " and the most playable of the Mizuno Pro series. More compact than the original with a revised CORTECH multi-thickness face for even quicker ball speeds. Equally effective as a long / mid-iron alternative for elite players or a complete set for low to mid handicaps. Grain Flow Forged in Hiroshima, Japan, with a soft copper underlay for a uniquely satisfying Mizuno sensation at impact. TECHNICAL DETAILS: Grain Flow Forged HD: One-piece Grain Flow Forged HD from 1025E Pure Select mild 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 Hot Metal Blade Design: Grain Flow Forged 4135 Chromoly Face & Neck (2-8 iron) combined with COR Forged Hollow Body. Hybrid Muscle Back: A high performance hollow body hybrid structure is formed by utilizing a Grain Flow Forged Chromoly Face and neck part, fused to multi-material body Multi-Material Construction: Strategically positioned exotic materials to help optimize launch and forgiveness Hollow Body Construction: Achieves optimized weighting through multi-piece construction 1025 Mild Carbon Steel: Soft mild carbon steel for an incredibly soft feel NEW Multi-thickness CORTECH Face: Refined to maximize the return from Mizuno's Beta Ti face. Ball speeds most noticeably improved low on the clubface.