EXPLANATION: What are the softshell helmet Guardian caps that Tua Tagovailoa says he won't wear?

MIAMI GARDENS, Fla. – Guardian Caps are soft, protective helmet covers that the NFL has allowed players to wear during games this season to reduce head injuries.

Several players have worn them in the first seven weeks, although Tua Tagovailoa, like most NFL players, said Monday that he will not wear the headgear when he returns from his latest concussion. Players have cited various reasons, including comfort and aesthetics, for not wearing them.

The NFL has required the use of caps during contact training for most players since 2022. Quarterbacks, kickers and punters are the only position groups not required to wear caps during contact drills that involve contact.

The league has approved six types of helmets that players can wear during contact drills that do not require Guardian Caps.

Tagovailoa has been cleared by medical experts to return to the Miami Dolphins after suffering his most recent concussion in a collision with Bills defenseman Damar Hamlin in Week 2.

If Tagovailoa clears the NFL's concussion protocol after practice on Wednesday, he is expected to start Sunday against the Arizona Cardinals.

Here's a look at the Guardian Caps and how they are used in the NFL:

What are Guardian Caps?

The 12-ounce padded shells attach to the top of a player's helmet. The NFL has stated that studies show that wearing the protective gear results in at least a 10 percent reduction in the severity of an impact for a player. This number increases to at least 20% if both players involved in a collision carry it.

There is no 100% shockproof headgear for NFL players

The league introduced eight position-specific helmets for quarterbacks and linemen this season. The position-specific helmets are not shockproof, but are intended to limit head trauma.

“Anyone can get a concussion in any helmet with the right hit,” Dr. Allen Sills, NFL chief medical officer, told The Associated Press. “What we always keep in mind is relative risk reduction. And when a player wears one of the best performing helmets, the risk of a concussion is definitely reduced. And that’s what our laboratory data and our field data have shown over the last eight years.”

The NFL says the Guardian Caps were effective

Last week, the NFL announced that it had experienced the fewest preseason concussions since tracking began in 2015. There were 44 concussions in practices and games, a decrease of about 24% compared to last year. The use of the Guardian Caps was one of the reasons league manager Jeff Miller cited for the reduction.

Who else uses the caps besides NFL players?

More than 300 college programs, 3,000 high schools and 750 youth programs across the country use the caps.

When were the caps created?

Guardian was founded in 2010 by Erin and Lee Hanson. The Guardian Cap was launched in 2011 and was available in 2012 after successful biomechanical testing and field testing.