A Mets protective batting helmet with a face shield extension. 

A Mets protective batting helmet with a face shield extension.  Credit: Newsday/Tim Healey

WASHINGTON — In a sport of bats and balls and gloves, the most critical piece of equipment in the opening days of the Mets’ new season has been a small piece of plastic invented by a surgeon in Atlanta four decades ago.

The batting helmet extension, sometimes wrongly referred to as a C-Flap, is the optional piece that helps protect a hitter’s jaw and cheek. It served its purpose well during the recent beanings of Francisco Lindor and Pete Alonso, who agreed with other Mets people who felt they would have suffered far more serious damage had they not been wearing the extra shield.

“It literally probably saved those two guys the last two nights,” said Kevin Kierst, the Mets’ equipment manager. “You’ll see it more and more.”

The helmet extensions have seen a “huge” surge in popularity over the past five years, according to Kierst, but they have been around since the early 1980s. That is when Dr. Robert Crow, a plastic surgeon and at the time Atlanta’s team physician, decided his hitters needed something that would keep them a little safer.

It was a natural next step for a now-ubiquitous accessory that for much of baseball’s history did not exist. In the same way that hitters progressed from using no helmets to using a helmet without an ear guard to using a helmet with an ear guard, some Mets and others have been adding the side face shield.

In addition to Alonso and Lindor, Dominic Smith and Robinson Cano are devotees of the helmet extension.

“We just want to protect ourselves, especially from freak accidents,” said Smith, who has worn it for a few years after noticing one-time beaning victim Giancarlo Stanton donning one. “It’s something that now I feel uncomfortable if I don’t have it on my helmet.”

Alonso said after his scare: “That’s why we wear it. If I wasn’t wearing that, I’d probably be missing teeth. I’m just happy I had that protection.”

The C-Flap moniker is a bit of a Kleenex/tissue or Xerox /photocopier situation. The original brand name isn’t the only option anymore.

Crow’s version is called the C-Flap, now produced by Markwort, a St. Louis-based sporting goods maker. But other companies in recent years have created their own.

Rawlings, for example, manufactures batting helmets for the majors and has an extension — called Mach Ext, to go with its Mach helmet — to match. That is what Lindor, Alonso, Smith and Cano wear.

Whereas previous versions required three bolts to lock it in, the Mach Ext snaps into place and is adjustable based on what a hitter is comfortable with. Kierst suggests hitters keep it high or else risk defeating the purpose, and he tests it by using a baseball to see if the gap between the flap and brim is small enough.

“You’re more worried about the orbital socket than anything,” he said.

Given recent Mets events, Kierst suspects more hitters will start using the extension. J.D. Davis said he will, after dabbling with it during previous seasons. Brandon Nimmo will consider giving it a shot during batting practice but said he felt he missed his chance to make the adjustment during spring training.

The extension does affect a hitter’s peripheral vision, Davis said.

“It’s one of those things where you get used to your vision, so you don’t really want to mess that up,” Nimmo said. “But I also get not wanting a ball to the mouth.”

Davis added: “It’s more of a preference and a comfortability. If you wear it all the time, obviously you’re going to get used to it.”

And the Mets won’t be the only ones increasingly turning to it, Kierst said. Because helmet extensions are commonplace in the youth, high school and college ranks, it seems inevitable that it will filter up through the minors and into the majors.

Manager Buck Showalter, his Friday night fury lessened a day later, kept repeating how lucky Lindor was that he wasn’t seriously hurt and praised the presence of the flap.

“It makes you wonder,” Showalter said, “why they’re not required.”

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