The Guardian Cap appears to be an effective tool in reducing concussions.
The NFL said concussions dropped by 50% this summer among players who were mandated to wear the piece of equipment.
The league compared concussion rates from the summer to the previous three years.
According to ESPN, the NFL required players in numerous positions, including linemen, tight ends and linebackers, to wear Guardian Caps from the start of training camp until the second preseason game.
The network reports that 11 players suffered concussions during that time, but six were caused by contact to the face mask, which the Guardian Cap does not protect.
Despite no longer being required to wear the caps, the NFL says some players are still using them.
Other players have complained about their fit.
The NFL says it will continue working on solutions to prevent concussions.
"When we started this work a few years ago, we said the offerings on the field may look a little bit different and I think we might be living up to those words. And, that's an exciting opportunity for the health and safety of the sport and for the players who play it," NFL executive Jeff Miller said, according to The Associated Press.