Mizuno Pro S-4 Irons Complete the Signature Series Lineup

Mizuno has added the Pro S-4 to its Signature Series, filling out a lineup of single-piece forged irons aimed at accomplished players who want more forgiveness than a traditional cavity-back or muscleback provides. The iron is available for pre-order starting Sept. 3 and ships to retail on Sept. 17 at $215 per club.

Where does the S-4 fit in Mizuno's Signature Series?

The S-4 is the third release in the Pro Signature Series, following the compact S-1 muscleback and the S-3 cavity-back. Mizuno Director of Golf Chris Voshall told GOLF the S-4 targets low-single-digit-handicap players who have been underserved as the industry pushed toward distance-focused irons. Compared with the S-3, the S-4 has a wider sole, more offset, a lower center of gravity and a redesigned, curved muscle in the cavity that shifts mass toward the toe and heel, raising forgiveness without adding a toe or heel bias.

What are the Mizuno Pro S-4's specs?

Each head is forged from a single piece of 1025E Pure Select Mild Carbon Steel using Mizuno's Grain Flow Forged HD process, with a copper underlay and Harmonic Impact Technology built in for feel. The iron carries Mizuno's Triple-Cut Sole, with beveled leading and trailing edges designed to help the club move through turf more consistently. It ships with a True Temper Dynamic Gold Mid 115 Stiff shaft and Golf Pride Z-Cord grip, and is available in a 3-iron through pitching wedge for right-handed golfers and a 4-iron through pitching wedge for left-handed golfers.

It's sneakily forgiving.

"It's sneakily forgiving," Voshall said of the S-4's performance. Mizuno positions the iron as a combo-set option, suggesting an S-3 player could move into the S-4 for their long irons, or an S-4 player could blend in one of Mizuno's M-Series irons for extra distance in the longer clubs.