Vertical integration isn’t a term you hear much in the golf-instruction business, but Martin Chuck has nearly every step of the process covered. The Golf Digest 50 Best Teacher manages golf schools that are sold out months in advance at the Tour Striker Golf Academy at Raven Golf Club in Phoenix. Those students are the test subjects for the popular array of Tour Striker teaching aids that Chuck has been inventing and selling for more than a decade.

Even if you don’t know Chuck’s training aids by name, you’ve probably seen one if you’ve been to a PGA Tour driving range. Chuck’s Smart Ball—a squishy, plush grapefruit-sized ball attached to a strap that goes around your neck—went viral in 2017 when Justin Rose and more recently Rory McIlroy used it on the practice tee at events.

The candid, unpaid social-media posts worked better than any organized advertising campaign and changed Chuck’s business model. “I don’t know Justin Rose and have never met him, and I look up and see posts of him using it,” Chuck says. “Then tour reps started calling and asking for a box of them so that they could hand them out when people ask. When Rory started using it and somebody posted about it, the interest literally broke our website.”

Chuck’s standard order from one of his worldwide manufacturing partners is 5,000 units. After the McIlroy post, his sales volume increased 100 times. “It went from 5,000 a year to 5,000 a month—and then we’d have weeks where we’d sell that many.”

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That explosive success made training aids much bigger than a side gig. Chuck’s wife, Stacey, now runs the business side of Tour Striker, and she fulfills orders with the help of two full-time employees at a small warehouse in nearby Gilbert, Ariz. “[Stacey] likes the business side, and I like the creative side, so we make a good pair,” Chuck says.

The Smart Ball helps to keep the chest and arms synchronized in the swing. The player holds the ball between the forearms and hits shots while trying to keep the ball in place until after impact. “I didn’t invent the concept of putting something between a player’s arms. I just built a better mousetrap,” Chuck says. “I got tired of chasing a ball down the range when a player would drop it, so I added my own strap. It was born out of laziness.”

Before the Smart Ball, Chuck created the Tour Striker Training Club, which gets players to swing through with the hands ahead of the clubface, and the Plane Mate, which uses a belt and rubber straps to pull players into better positions through the swing. Currently, Chuck’s test subjects are using two experimental training aids that typically hit the market eight to 18 months after testing. “The ideas start from the place of What can help me?” says Chuck, who played mini-tours in Canada before switching to coaching in the mid-1990s. “I still love to play, and I love to hit the center of the face. What kind of tricks are out there to make that happen?”

If earning more than 250,000 customers and selling a freighter’s worth of $47 Smart Balls wasn’t enough market validation, the Chucks got the ultimate bit of positive feedback on a recent vacation in Rome. Martin and Stacey took in a day of Ryder Cup action as spectators. When they got to the grandstands at the Marco Simone practice area, four players, including Rose and 2022 U.S. Open champion Matt Fitzpatrick, were using Smart Balls to warm up. “So cool,” Chuck says. “It makes me want to come up with the next one.”

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This article was originally published on golfdigest.com