“Hot Metal has become a monster,” says Mizuno’s Chris Voshall, Mizuno USA Golf Product and Marketing Manager.
It’s hard to overstate what the introduction of the Hot Metal franchise has meant to Mizuno but to put things in perspective, it’s worth stepping back in time.
For all its prowess in the player’s iron category, there was a good run where Mizuno wasn’t considered a serious player in game-improvement space.
Exhibit A
That might be my earliest digression ever.
Anyway …
In 2017, Hot Metal’s first year on the market, it accounted for 3.51 percent of dollars spent on irons. Its share has grown steadily with each release.
In 2020, Mizuno had bit more than an 8.5 percent share of the iron market. By 2023, that number had increased to 12.5 percent with 9.71 percent coming from JPX product. Most of it (7.19 percent of the market) was Hot Metal.
In full context, Hot Metal on its own is nearly all of what the totality of Mizuno iron sales used to be.
Even with that success, I’d be inclined to describe the JPX Hot Metal family as a bit of an anomaly in the game-improvement space. Most of what you’ll find in the category are loft-jacked, overtly tech-rich designs that leverage a variety of materials and assorted cream fillings.
By comparison, Mizuno has generally been more sensible about lofts (the JPX 923 Hot Metal HL was among the first to offer weaker lofts) and, while Hot Metal could hold its own performance-wise against nearly anything on the market, Mizuno did what it did without pulling any of the levers competitors use to juice their designs.
While everyone else was using multi-piece, multi-material designs, Mizuno’s JPX Hot Metal relied entirely on single-piece construction.
With the JPX 925 Hot Metal, that changes.
Mizuno JPX 925 Hot Metal – 3 models
As with the JPX 923 line, Mizuno is offering three distinct flavors of Hot Metal. You get the middle-of-the-road standard JPX Hot Metal, the more player-centric Hot Metal Pro and the more forgiving, slower swing-friendly Hot Metal HL.
As was the case last time around, the three models share a common platform and common technology. What’s true for one is true for all three. Only the size and specs (length, loft, etc.) differ.
What JPX 925 Hot Metal brings to the table
The summary of JPX 925 benefits includes more consistency across the face (improved forgiveness), more speed from the center and higher launch.
So, with that, let’s look at what Mizuno has done to enhance the performance of its best-selling iron family.
New CORETECH
Your briefest of refreshers: CORETECH is Mizuno’s face technology that brings with it the industry-standard objective of preserving more ball speed over more of the face.
You might recall that JPX 923 Hot Metal was the first time Mizuno used Nickel Chromoly 4335+ as its material of choice. The unwritten rule with any new material is to take a conservative approach to engineering. “We maximized performance with one foot in the make sure it doesn’t break camp,” explains Voshall.
The specific area of concern was what Voshall calls the hinge piece in the lower portion of the JPX 923 Hot Metal face. Erring on the side of caution, Mizuno made the hinge a bit thicker than was perhaps necessary or ideal and, with that, it left some performance on the table.
Two years removed from JPX 923, Mizuno’s confidence in Chromoly 4335+ has grown and it feels it can be more aggressive in how it leverages the materials.
That confidence manifests itself in a new approach to a variable-thickness face design. The updated topology includes areas Mizuno call flex zones that are just 1.2 millimeters thick. Comparable areas of the face were 1.9mm thick last time around. Areas around the perimeter have been thinned as well.
The rule of thumb in face design is that thinner is faster. By thinning both the sweet area and the perimeter, Mizuno is able to deliver a bit more speed.
The variable-thickness concept is also baked into the sole. Thicker areas provide strength where it’s needed while thinner areas work to improve low-face performance compared to JPX 923 Hot Metal.
All of this is part of the larger objective to provide peak COR (or at least close to it) over as much of the face as possible. Mizuno’s data suggests the new Hot Metal and Hot Metal HL are among the very best in the industry. Warning letters from the USGA would seem to support the claim.
Hot Metal Pro is a bit of an exception among the three. While it still offers plenty of speed, the sweet area isn’t quite as large because of the smaller face.
A bigger face means a bigger trampoline.
(Secret) tungsten
Even though I’m all but obligated to mention it, tungsten itself is not typically all that notable. Besides, manufacturers are more than happy to note it for me. Seldom is an opportunity missed to stamp “tungsten” on a head. I swear, it feels like a licensing issue where if you use tungsten it has to be credited where everyone can see it.
Getty’s photo rules are less restrictive.
Anyway …
Mizuno’s approach is different in that, in the interest of keeping things as clean as possible, it decided to forgo denoting the tungsten anywhere on the head, but I swear it’s there.
This is all just the really long way to tell you that the JPX 925 4-7 irons feature internal tungsten weights.
The ripple in Mizuno’s implementation is that the weight is explicitly low-ish and forward instead of low and back. True to the Hot Metal philosophy, Mizuno is seeking to increase launch without dropping spin below sensible levels.
Playability is still the goal.
With the addition of tungsten, Mizuno is realizing a couple of other benefits. The first is increased inertia (MOI). The tungsten weight also works to pull the CG closer to the hosel (closer to center) which helps make the new Hot Metal easier to turn over.
If you want to call that a bit of relative draw bias, that’s probably fine.
JPX 925 Hot Metal Pro
JPX 925 Hot Metal
JPX 925 Hot Metal HL
Improved feel
Even with its cast models, Mizuno emphasizes feel. So while Nothing Feels Like a Mizuno is generally the stuff of its forged lineup, JPX Hot Metal shouldn’t feel clangy. At the same time, Mizuno doesn’t want to fill Hot Metal with goo to dampen feel entirely.
Much like Marky Mark, Mizuno wants to you feel the vibrations, but in a good way (and with a proper pair of pants on).
When it comes to feel, a good bit of what we experience comes down to geometry. In the case of the JPX 925 Hot Metal, its about the placement of support structures that work to tune sound. Specifically, Mizuno has leveraged a series of ribs to provide rigidity along the topline and a soundbar that runs through the center of the back cavity.
We’ve covered the science of feel before but the general idea is that if you can successfully target the desirable frequencies for the right duration, golfers are likely to say your irons sound and feel good.
If you’re looking for the specific improvement, it’s that Mizuno has lessened sound pressure in the frequency range from 6,000-9,000 Hz .
And while that feels like the sort of thing that should be on a test, the only thing that matters is that Mizuno says the new JPX Hot Metal feels more solid and hot and less tingy than before.
Looks
All three Mizuno JPX 925 Hot Metal models offer clean lines. You won’t find any ornate multi-color cavity badges. There’s minimal stamping and the only notable change is a small splash of color in the corner of the cavity badge.
The standard Hot Metal has white. Hot Metal Pro is black and Hot Metal HL has blue accents.
The intent isn’t to bling anything out. Mizuno just wanted to make it a bit easier for fitters to find and pull heads during the fitting process.
Mizuno JPX 925 Hot Metal – Spec changes
With the 2025 models, Mizuno has made a few spec changes throughout the Hot Metal lineup.
Stronger lofts
With the JPX 925 Hot Metal, the 9-iron and pitching wedge are half a degree stronger. Hot Metal Pro is half a degree stronger in the 7 to gap wedge. And while I suppose it’s technically not a loft change, Mizuno has added a 4-iron to the Hot Metal HL offering and dropped the lob wedge.
It’s a small change meant to bring Hot Metal closer to what loosely passes for industry-standard lofts.
More upright
Similarly, Mizuno has made its stock lie angles .5 degrees more upright across the board. Likewise, irons are .5 more upright. They’re still a bit flatter than most.
To an extent, none of this is particularly important since you can bend Hot Metal anyway you want them.
Longer lengths*
On paper, the JPX 925 Hot Metal iron family is ¼” longer than the previous models. The actual length is the same.
One of the goofy things in the golf equipment industry is proprietary rulers are not uncommon and wi,th that, not everybody agrees on how to measure. Previously, Mizuno used its own ruler. With JPX 925, its measuring the USGA way so while actual lengths are the same, the published numbers have changed.
The exception is the wedges which are actually slightly shorter with JPX 925 Hot Metal.
Speaking of wedges …
In prior iterations of Hot Metal, Mizuno took a universal approach to wedges. There was a single Hot Metal wedge design that split the difference (more or less) between the individual models.
This time around, Hot Metal and Hot Metal HL have distinct wedge offerings. It should make things a bit more seamless for the guy who prefers set-matched wedges
JPX 925 Fli-Hi hybrids
For golfers who need a little extra help, particularly at the long end of the set, Mizuno will again offer Fli-Hi hybrids as direct long-iron replacements. And just like last time, they’re priced the same as the irons they replace.
Designed to be a like-for-like swap, Fli-Hi hybrids will typically be outfitted with the same shaft as the rest of your Hot Metal iron set (though feel free to go in a different direction if you’re so inclined).
Progressive shapes
The most noticeable change from prior models is the footprint of the JPX 925 Fli-Hi hybrids. The 925 models are designed to flow better which ultimately means that they get progressively more compact from front to back as you move up in loft. With that, not only do you avoid larger shapes where they’re not necessary but the spin profiles of the Fli-His are now closer to that of the irons they replace.
Speed Bevel sole
JPX 925 Fli-Hi hybrids offer what Mizuno calls “Speed Bevel.” What we’re talking about is a tweak to the leading-edge geometry that creates a bounce surface that helps the club move through the turf. Said another way, Speed Bevel makes Fli-Hi hybrid a bit more friendly to negative attack angle swings associated with iron play.
Improved Wave Sole
On metalwoods, every manufacturer has technology designed to improve speed on low-face impact. On Fli-Hi, it’s Wave Sole. With the JPX 925 Fli-Hi, Mizuno has improved Wave Sole performance to preserve more speed on low impact.
Finally, Mizuno has made a small cosmetic change to the score lines to better frame the ball at address.
JPX 925 Fli-Hi options
JPX 925 Fli-Hi hybrids are available in four lofts: 19, 22, 25 and 28 degrees. The specific iron each replaces depends on which Hot Metal set you’re sliding it into but, broadly, think of Fli-Hi as an option to replace anything from a 4- to 7-iron. That gives you plenty of flexibility to take Fli-Hi deep into your set and not pay through the nose for the privilege.
Mizuno JPX 925 Hot Metal and Fli-Hi specs, pricing and availability
The stock shafts for the JPX 925 Hot Metal are the Nippon NS Pro 950 NEO (steel) and UST Recoil Dart ESX (graphite). The stock grip is the Lamkin UT+.
Stock shaft offerings for the JPX 925 Hot Metal Pro are the Dynamic Gold 105 (steel) and Mitsubishi MMT (graphite). The stock grip is the Lamkin UTX+ (cord).
The stock shaft offerings for the JPX 925 Hot Metal HL are the Dynamic Gold 95 (steel) and UST Recoil Dart ESX (graphite). The stock grip is the Lamkin UT+.
The stock shaft for the JPX Fli-Hi is the UST Recoil Dart ESX, though the expectation is that most golfers will choose to match their iron shafts. The stock grip is the Lamkin UT+.
Mizuno JPX 925 Hot Metal irons are available in right- and left-handed. Left-handed options in the JPX 925 Fli-Hi hybrid are limited to 19 and 22 degrees
Retail price for the everything in the JPX 925 Hot Metal family (including Fli-Hi) is $150 per club.
Pre-sale for the Mizuno JPX 925 Hot Metal begins Sept. 5. Full retail available starts Sept. 19.
For more information, visit Mizunogolf.com.
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