A year before the most important decision of his life, Bryce Harper made one with that future in mind last winter, one on display every time he’s stepped into the batter’s box this season. It’s a piece of plastic across the right side of his face, the side facing the pitcher, attached to his batting helmet. It’s called a C-Flap, named after the man who invented it in his kitchen nearly 40 years ago, and it affords Harper an additional sense of safety at the plate.

A specific event didn’t spur Harper to add the apparatus. He has never been hit in the face by a pitch. But pitchers are throwing harder than ever. One wild flash could cost weeks on the disabled list, or worse, and millions of dollars in free agency this winter. So he decided he would work with the extra armor over his check and jaw this season.

“Why not?” asked Harper, 25.

It’s a question an increasing number of players across the majors have asked in the last few years. Until recently, C-Flap sightings were rare. They were taboo – too goofy and too cumbersome in a sport bursting with machismo – and used only when a facial injury rendered them absolutely necessary. Even then, they were temporary. Those aesthetics concerns have seemingly faded. Now, some of the sport’s top stars, previous facial injury or not, have made the C-Flap as standard as a cap and mitt.

Jason Heyward was the first to adopt the guard permanently, and his decision wasn’t voluntary. He only began wearing it after 90-mph fastball hit him flush in the face and broke his jaw in 2013. It was a scary scene, and it sparked a subtle movement.

Giancarlo Stanton, Mike Trout, Carlos Correa, Kris Bryant, Jose Altuve, Yadier Molina and Miguel Cabrera are all C-Flap converts. The list goes on throughout the major leagues into the minors – and it’s growing.

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Dr. Robert Crow was a plastic and reconstructive surgeon working for the Atlanta Braves in the 1970s when he encountered a problem: players recovering from facial injuries didn’t want to wear the protection available. The devices were too bulky or interfered with their vision or impeded breathing. But they needed something, so Crow set about finding a solution in his kitchen. He initially created the C-Flap with othoplast, the plastic used for splints, and took prototypes to Braves spring training to have players try them out before they were sent to Wayne State University in Michigan for impact testing. He called it a C-Flap after his last name and what it protected – the cheek.

“It was made to, number one, not interfere with vision, to allow the access to the mouth, the airway, and to not look like an added-on piece,” Crows said. “In other words, it was colored to match the helmet so it looked like an extension of that rather than just a piece of equipment that was put on for protection.”

Crow was granted patents in the United States and Japan by the late 1980s, and distributed his product to stores and leagues until he sold his small company to Markwort Sporting Goods in 2004. Initially, C-Flaps made up less than 1 percent of the St. Louis-based company’s sales, but sales have tripled each of the past three years, according to CEO Herb Markwort, with boosts from popularity in Korea and Taiwan. C-Flaps currently comprise around 15 percent of Markwort’s business, and the share continues increasing.

“For a product to be 38 years old and, at the 35-year mark, all of a sudden start taking off, growing, tripling sales, is just unheard of,” Markwort said. “And we don’t pay any of these guys to wear it. We don’t give any of the guys free products to use. It’s just the product itself selling itself.”

Rawlings, Major League Baseball’s helmet manufacturer, buys the C-Flaps from Markwort and distributes them to clubs and their minor league affiliates. While individual players at the major league level decide whether they want to attach it on their own, the Milwaukee Brewers were the first team to require all minor leaguers to use C-Flaps this season.

Herb Markwort pinpoints the surge’s genesis to Heyward getting hit in the face in August 2013, when he was with the Atlanta Braves. The next year, an 88-mph fastball plunked Giancarlo Stanton, then with the Miami Marlins. He suffered facial lacerations, multiple fractures, dental damage and was carried off on a stretcher. In April, Chicago Cubs third baseman Kris Bryant – now Heyward’s teammate – was hit in the head, though he avoided serious injury. All three wear the C-Flap, and the incidents motivated others to do the same. Last year, Brewers outfielder Keon Broxton credited his C-Flap for saving his life after getting hit by a fastball in the face.

“Some of the people have given [Yadier] Molina here in town credit for being one of the first major league baseball players to wear it before he got hit, just as a preventive measure,” Markwort said, referring to the St. Louis Cardinals catcher. “So the lightbulb went off and a lot of other people thought, ‘I should probably wear it too before I get hit.’ ”

Amateur players, however, are effectively forbidden from attaching C-Flaps to their helmets because most baseball governing bodies, including the NCAA, abide by the rules the National Operating Committee on Standards for Athletic Equipment (NOCSAE) have established. And those standards deem drilling holes in a NOCSAE-certified helmet, which is necessary to attach a C-Flap, voids the helmet’s certification.

Rawlings and other companies are expected to enter the market with NOCSAE-approved helmets with holes for flaps pre-drilled by the end of the year to serve the amateur and, effectively, professional markets – and challenge Markwort’s dominance. For now, amateurs are encouraged to wear wire guards – resembling football masks – for facial protection. Numbers indicate they don’t want to. Markwort said wire guard sales have dropped 90 percent in the last decade and have fallen another 64 percent this year.

“Kids want this helmet,” Rawlings executive vice president of marketing Mike Thompson said. “Kids want to wear the flap. Kids see stars wearing it and it’s like anything: They want to be like their heroes.”

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C-Flaps aren’t for every major leaguer, at least not yet. Harper is the only player on the Nationals’ current roster using it, though Jayson Werth and Raudy Read both wore them last season. Ryan Zimmerman said he’s never thought about utilizing it. Matt Wieters said it doesn’t make sense for him because, as a switch-hitter, he’d be on the opposite side. If he gets hit in the face, he figures, it’d be on purpose.

Matt Adams spent his first six major league seasons with the Cardinals and Braves, playing with Molina, Heyward, Kolton Wong, Dansby Swanson and others who have joined the burgeoning C-Flap faction. But he hasn’t given it a try.

“I feel like my head would be lopsided,” said Adams, now with the Nationals. “I’d need time to get used to it.”

Harper used batting practice in the cage during spring training to become accustomed to the apparatus. Meanwhile, Tampa Bay Rays and former Nationals catcher Wilson Ramos made the adjustment in May on the fly.

“I’ve seen various players from various teams that have used it,” Ramos said in Spanish. “I initially thought it would bother me, but the truth is it doesn’t affect me at all. I feel comfortable. I feel a little more protected.”

While Ramos’s decision was precaution-fueled, Philadelphia Phillies outfielder Rhys Hoskins is the latest to have been pushed to using the C-Flap because of an injury – and he’s taken it to an extreme. The frightening scene occurred on May 31, when he fouled a pitch off his face and suffered a fractured jaw.

Hoskins, 25, was given a choice: miss four to six weeks or return after 10 days on the disabled list with a C-Flap on both sides for complete armament. Hoskins opted to return early with the double-C-Flap look and has batted .310 with five home runs and a 1.044 on-base-plus-slugging percentage in 15 games with the unconventional safeguard.

Hoskins said his C-Flaps are a little lower than others’ because they’re designed to protect his jaw more than his orbital bone. He’ll shed the right half of the shield when his jaw heals, but will continue using the C-Flap on the left side. It all comes down to one question he and dozens of others have asked: Why not?