Mizuno JPX 921 Forged irons are forged from a single piece of chromium molybdenum steel (Chromoly 4120) with Mizuno’s Grain Flow Forged process for a real Mizuno feel at the moment of impact. The boron-reinforced steel allows the face to be thinner, which makes it hotter and generates high ball speed. With a shorter blade length and reduced offset, you get a slender profile at address. A precision milled channel behind the thin face creates high ball speed across the entire face which gives consistent distance. Mizuno’s Stability Frame technology goes around the back of the club with an extra weight in the toe which helps you achieve consistent ball flight. The matte Pearl Brush finish eliminates reflections at address.