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John Isner’s Racquet Setup

The greatest server of all time has been ranked in the top 30 for most of his career. Though he might be prioritizing life outside of tennis having recently become a father of two, John Isner can still bash the ball with the best of them.

He’s played the longest match on tour at a hair over 11 hours and has hit the official fastest serve at 253 km/h (157.2 mph).

Let’s take a look at which racquet the former world number 8 uses while he’s dropping bombs

Isner and His Prince Racquets

John had a reputation in college at the University of Georgia for buying his old, discontinued Prince triple threat racquets off of eBay in just about any condition or grip size.

He claims he never even checked the specs. Afterward, when he started playing on the tour, he switched to a prince o3 White 100. Some reports say he had prince make a custom 18×20 string pattern version of the racquet for him, but there are pictures of him playing 16×19 as well.

For the entirety of the time O3 and Speedport were the flagship Prince technologies, John played the O3 white 100 under various paintjobs like the Exo3 Black and Exo3 Warrior.

John’s racquet in the EXO3 Warrior paintjob was available from a pro stock racquet seller. It’s a bit difficult to see that his O-ports are circles because the borders around the holes were painted square, like the retail model, but it’s still the O3 white beneath. 

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Since Prince’s restructuring and foray back into the mainstream with non-ported racquets, John has used the Prince Textreme Warrior 100 and then a Prince Beast Pro Longbody 100 paintjob.

According to an interview with Tennis Warehouse back when the Beast Pro LB came out, Isner actually uses this frame, and the stock specifications are his personal ones.

Whether that’s the truth or just marketing, it’s tough to tell, but the specs are almost dead on to what his older 03s were, and the Beast and Warrior molds are very similar if not the same. He states in the video that Prince consulted him on this racquet and effectively made it for him. 

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As mentioned, John uses a racquet that’s been extended half an inch. He also adds a bit of weight to his frames.

His O3 white specs have been reported by multiple reputable sources as 346g, 33.1 cm balance, and 350 swingweight strung up with an overgrip. It’s safe to assume he has stayed close to this with his un-ported frames.

Stringing On Two Ends of the Spectrum

While it is true that most of the pro tour has moved toward lower string tensions, John Isner seems to have taken that to the extreme.

Back when he was younger, he strung full 16 gauge polyester, Tecnifibre Red Code most of the time, in the high 60s. Now, he’s on the completely opposite end of the tension range down at 35 pounds.

During the aforementioned Tennis Warehouse interview, he mentioned stringing anywhere between 47 and 54 pounds depending on conditions. He’s obviously dropped even lower. 


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John Isner is obviously a player who keeps it simple. He’s made a few incremental changes in his time on tour but never anything radical…save the string tension.

Considering his massive serve and power off the ground can keep his points short and ease the toll tennis takes on his body, it would be no surprise to see him continue swinging his Beast of a racquet for a few more years out on tour!

If you’re interested in other ATP players’ racquets, I listed all the top 100 players’ racquets in this post.