The facial mask has long been a staple of football, as it helps prevent injuries to the face.
But experts are now suggesting it should be more than just a basic protective device for players and coaches.
The NFL has made its new guidelines public ahead of Week 13, with some teams including masks that have been worn for a week.
“The helmet is an absolute safety blanket,” head of football safety Gregg Williams told reporters in the league’s annual meeting in Orlando.
“It’s like an extra layer of protection.
You need to be careful with it.”
The NFLPA’s head of safety and health, DeMaurice Smith, added: “If you want to be the best, you need to protect yourself.”
The helmet, or headgear, is also required for players, coaches and referees.
But it can be difficult to buy the right type, with brands typically sold at sporting goods stores or online.
“There are a lot of brands, and you’ll get a lot more bang for your buck if you go to a sports store,” former NFL player Chris Borland told BBC Sport.
“I don’t know if you want it in a helmet.
It’s just a helmet, with a visor.
If you want a different visor, you have to buy it.
But the mask is essential. “
If there’s a problem with it, I’m going to buy a different helmet.
But the mask is essential.
It makes your life much easier.”
For more sports news, go to BBC Sport’s website.