The Mizuno Pro M-15 is the next evolution of forged performance — offering higher launch, added forgiveness, and a smoother flow from long iron to wedge. Grain Flow Forged Chromoly: Our strongest Forged material with the solid, soft consistent feel of Grain Flow Forged Hot Metal Blade Design: Grain Flow Forged 4135 Chromoly face and neck (2-8 iron) with multi-thickness configuration and laser welded 431 Stainless steel back piece for elevated ball speeds and launch. Partial Hollow Scoring Irons: Laser welded partial hollow construction, GFF HD 1025E Select body, with 17-4 back piece for penetrating flight. Copper Underlay: Thin copper layer beneath a nickel chrome to provide a further enhanced impact feel Harmonic Impact Technology: Fine tuned head geometry delivers ideal impact feel and feedback 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 1025 Mild Carbon Steel: Soft mild carbon steel for an incredibly soft feel