Mizuno has long been hailed for their forged irons, and their newest addition, the Mizuno Pro S-1 irons, promises to be more of the same. They are pure muscle back irons and are apart of the brand’s Signature Series. The S-1 is built for elite players seeking better precision, consistency, and that unmistakable Mizuno feel.
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Here’s everything you need to know about the Mizuno Pro S-1 irons…
Mizuno Pro S-1 Irons: The Technology
While the Mizuno Pro S-1 honours Mizuno’s strong history when it comes to irons, it is by no means stuck in the past. In fact, this model debuts several refined technologies that elevate it beyond a standard muscle back.
Rather than a traditional solid muscle, the S-1 features a Channel Back geometry. This redistributes weight vertically for a more stable centre of gravity, enhancing launch consistency while maintaining workability. The feel is a slightly more solid, tour-preferred sensation., giving precise, confident feedback without compromising on Mizuno’s renowned softness.

There is also no shortage of innovation when it comes to the materials used. The S-1 irons are forged via Mizuno’s exclusive Grain Flow Forged HD method in Hiroshima, Japan. This is used to create a tighter grain structure using 1025E Pure Select Mild Carbon Steel, giving the S-1 its signature buttery feel. The addition of a copper underlay subtly enhances vibration dampening, fine-tuning the impact sensation to what Mizuno describes as the ultimate sensory connection.
Working hand in hand with the Channel Back, Mizuno’s Harmonic Impact Technology, H.I.T., adjusts vibration frequencies through the head for a more solid yet controlled feedback. It is also to help promote a more pleasing sound and feel at impact.
One of the most notable upgrades from previous Mizuno muscle backs is the sole geometry. Drawing direct input from tour professionals, the S-1 features a flatter camber for better turf interaction, a sharper leading edge for a cleaner entry into the ground, as well as increased bounce to reduce digging.
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With the S-1 joining the Mizuno Pro family, it accompanies the already-popular S-3 irons which were released earlier in the year. Where the S-3 offers slightly more playability for a broader range of players, the S-1 stands as the purist’s choice, purpose-built for shotmakers who demand precision from every angle.
Let’s take a closer look at the latest addition to Mizuno’s Signature Series…
Mizuno Pro S-1 Irons: The Line-up

Looks: They are pure muscle backs.
Main Attributes: Delivers top level shot-shaping, trajectory control, and precise feedback
Who is it for?: The Mizuno Pro S-1 is designed for the more accomplished ball-striker.
The Details
Available: Now
RRP: £215/$215 per club
Shafts:
- KBS Tour 120 Stiff
Grip:
- Golf Pride Tour Velvet
Set
- 4-PW / RH and LH
Models: Mizuno Pro S-1 Irons
More Information: Mizuno UK / Mizuno US
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