Back in January, we brought the information on the first entry within Mizuno Golf’s Signature Series, the S-3 irons. That release was the beginning of something new, but also a pivot of sorts to make sure that they also stayed true to their roots.
As we have come to know, both the Mizuno Pro and JPX lineups have been at the forefront of iron innovation, constantly creating lineups that set a standard in the industry. The Signature Series however, was created as a way to ensure that they also had options which took the needs of the modern golfer and melded them with undeniable Mizuno tradition.
When the S-3 were introduced, Mizuno told the world that the Signature Series would be a long-lifespan limited creation which would exist over many cycles. They also made it clear that it was just the beginning, and that is why today they are officially announcing the addition of the Mizuno Pro S-1 irons.
Mizuno Pro S-1 Irons
While the S-3 irons are as clean and classic of a split cavity design which the golf industry has seen, many were surprised that the first Signature Series release was not a muscle-back. After all, when you think pure player’s irons from Mizuno, most minds inevitably wander to some of the most legendary blades of all time.
The S-1 delivers arguably the most innovative yet classic MB yet from Mizuno. These irons are all about precision and workability, which makes sense given that they are the type of club which only the best ball-strikers typically dare to use. The S-1’s use Mizuno’s foundry in Hiroshima, Japan to utilize their Grain Flow Forged HD Process to take a single billet of 1025E Pure Select Mild Carbon Steel and create these works of art.
Additionally, the beloved Copper Underlay is also present, as is the Soft White Satin finish which matches the S-3’s. These are all also part of Mizuno’s Harmonic Impact Technology which takes into account every single material, application, radius, and much more to fine tune the irons within specific hertz zones. That is a critical element to why “Nothing Feels Like a Mizuno”, and the S-1’s certainly aim to live up to that slogan.
While there is a limited number of things that you can do to a muscle-back compared to a modern cavity-back, Mizuno collaborated with their Tour players to ensure no stone was left unturned with the S-1. The “channel back” design on the rear of the club allowed for the movement of mass to not only increase the vertical stability of the irons but also create a much more consistent CG placement than most traditional MB designs.
The overall shaping is as compact as one might expect, keeping the topline thin and the offset minimal. One of the more unique changes though when compared to the 241 MB’s is that the toe shaping with the S-1 is much squarer, this was done via direct feedback from some of the best ball strikers Mizuno works with on Tour. Also, the sole is flatter here with less camber than the 241, this combined with a sharper leading edge and one-degree of added bounce means that the S-1 is aimed at working best for those with a shallower angle of attack to ensure less digging and optimal workability.
The Details
It is crystal clear that every single addition to the Mizuno Pro Signature Series is going to be not only art but designed with the most confident ball strikers in mind. The S-1 irons will be offered in 4-PW (RH/LH) and paired with the KBS Tour 120S and Golf Pride Tour Velvet grips as standard options. Pre-sale begins 8/28/25 and coming to retail release on 9/11/25.
For more information visit their website mizunousa.com.
