Mizuno JPX 921 Hot Metal Golf Iron – Steel The Mizuno JPX 921 Hot Metal Golf Irons in Steel pair Mizuno’s fastest ever ball speeds with a piercingly straight ball-flight and controllable landing angles. Features & Benefits Faster Chromoly 4140M Mizuno’s 3rd generation of designing and manufacturing irons using Chromoly – now taken to its limits. A re-engineered CORTEC face is now 0.2mm thinner across the center point. Seamless Cup Face A new variable thickness sole design allows the leading edge to act as a hinge, resulting in greater face flex and ball speeds. Harmonic Impact Predicting vibration patterns dictated 3 additional sound ribs – producing a more solid sensation. Pearl Brush Finish Anti-glare to minimize distractions over the ball. Stability Frame Extreme perimeter weighting with toe bias for stability from off-center strikes.