Defending PLAYERS champ Justin Thomas uses special 1-of-1 irons

It’s not uncommon for PGA TOUR players to give their golf clubs a unique touch with custom stampings. Whether it’s their initials, family members’ names or movie quotes, the paint-filled engravings can add a special flair to their tools of the trade.

While Justin Thomas’ current Titleist “621.JT” irons do have his initials stamped on the hosel, the stampings aren’t the only unique feature of the clubs. The irons are actually 1-of-1 prototypes made specifically to meet Thomas’ personal preferences.

He is arguably the best iron player of the post-Tiger era, having finished no worse than sixth in Strokes Gained: Approach in each of the last six seasons. His iron-play prowess was on full display in his victory at last year’s THE PLAYERS. After flirting with the cut line Friday afternoon, Thomas shot 64-68 on the weekend while displaying full control of his ballstriking. He hit the first 17 greens in the final round, as well.

He used a set of stock Titleist 620 MB (muscleback) irons here last year. Those clubs were released to the public in 2019.

The blade-style construction of the stock 620 MB blades featured thin soles, thin toplines, compact shapes and little offset. The problem is, however, that Thomas doesn’t want “little” offset; he wants none.

As a reminder, the term “offset” refers to how far the leading edge of the face sits behind the hosel. By general rule, the more offset an iron has, the it is to square the face at impact. Many TOUR pros use irons with reduced offset to avoid hooking the ball too much, whereas amateurs tend to use irons with more offset to reduce their slice. Most golfers, though, even on the PGA TOUR, use some semblance of offset to add forgiveness. But not Thomas.

Although Thomas helped provide Titleist with early feedback on the 620 MB irons, as Titleist tour rep J.J. Van Wezenbeeck explains below, he would have his gamer irons bent to remove any offset.

“The biggest thing is we’re always trying to work with our TOUR pros on finding things that will help them play better,” Van Wezenbeeck told GolfWRX. “Justin’s been an important part of that feedback loop in our development of muscleback irons over the years. Throughout his career with Titleist, we’ve taken his feedback, talking to him about sole design, toe shape, etc. So, as we brought (620 MB) prototypes to him, he was able to provide feedback and he really allowed us to move that into what became the 620 MB. Based on what we looked at over time, one of the facets he likes is no offset. Not a little offset, but none. Literally zero offset, so the leading edge and the hosel are in-line with each other. That’s obviously not something preferred by all players, so what we were doing for the 620 MBs for him was bending the offset out.”

The offset modifications helped provide the look and performance that Thomas needed, and he used the purposely-bent 620 MB irons to win at TPC Sawgrass last year.

Bending irons, however, doesn’t always create the perfect sound, feel and most elegant overall look. Unsatisfied, Titleist sought to provide Thomas with the exact irons he wanted in all facets.

“We wanted to provide the best looking, best feeling and best performing irons for one of the best iron players on Tour,” Van Wezenbeeck said.

That’s when Titleist and its R&D team started working closely with Thomas to develop what would eventually become the 621.JT irons.

They built a number of prototypes with differing shapes, soles, CG (center of gravity) placements, and offset to determine what truly suits Thomas’ preferences.

What they settled on were irons that were essentially identical to the original 620 MB irons in terms of overall shaping, sole grinds, materials (1020 carbon), and grooves. The only true difference is the 621.JT irons have zero offset, which is just how the defending PLAYERS champ likes them.

“They came to me and said let's create (a set of irons), anything that you want to change,” Thomas told PGATOUR.COM. “Obviously I loved it, everything about (my irons) already, but the changes are so minor. … It just was about getting the best feeling iron, the best sounding iron. It's one of those clubs that obviously you have to hit it properly for it to be that way, but one of those ones where you kind of hear it and you turn around like, ‘What is that?’…They look awesome.”

Thomas started using the new 621.JT irons at the 2021 CJ CUP @ SUMMIT in November 2021, and he still has them in the bag this week to defend his title at THE 2022 PLAYERS Championship. While he is looking for his first win since last year’s PLAYERS, Thomas is ranked 26th in this season’s FedExCup thanks to four top-10s in six starts.

There are plenty of interesting JT-related equipment stories out there, but this tale of how a 15-year-old junior golfer inspired him to wise up and return to his old putter is a great one.