(NEXSTAR) – If you’ve been watching any NFL games recently, you might have noticed some players sporting white (or in some cases, black or blue or red) horseshoe-shaped collars around their necks.

While they seem more widespread now, they aren’t new. Some players, like ex-Carolina Panthers linebacker Luke Kuechly, wore them as early as 2016. 

They’re known as the Q-Collar and are intended to protect the wearer’s brain during head impacts. The marketing of Q30 Innovations’ Q-Collars was authorized by the Food and Drug Administration in 2021. At the time, the agency said they “may reduce the occurrence of specific changes in the brain that are associated with brain injury.”

When anyone’s head or body is hit, regardless of whether they’re an athlete or not, they could suffer a traumatic brain injury, or TBI. According to the National Institute of Neurological Disorders and Stroke, a leading cause of TBI is blunt trauma accidents. 

During blunt trauma accidents, your brain typically moves unrestrained in the skull in what is often described as a “slosh,” the FDA explains. 

The Q-Collar, according to the FDA, compresses against the jugular veins in the wearer’s neck. This is meant to increase the volume of blood in the skull’s vessels in order to create “a tighter fit of the brain inside the skull.” That tighter fit can then reduce the “slosh” movement.”

It isn’t just NFL players and athletes sporting Q-Collars. Q30 Innovations was awarded a $2.8 million contract by the U.S. Army Medical Research and Development Command to fund research and development of the Q-Collar to determine if it can reduce blast-induced TBIs among soldiers. 

So why isn’t everyone wearing one?

While the FDA authorized the product for marketing, the agency did warn at the time that Q-Collars shouldn’t be used by athletes with certain conditions. It also noted the collars cannot prevent concussions or serious head injuries. 

Even Kuechly suffered a concussion in the weeks after he began wearing the Q-Collar.

Adil Hussain, D.O., a physical medicine and rehabilitation doctor who specializes in brain injury medicine at Rancho Los Amigos National Rehabilitation Center in California, told ABC News after the FDA’s authorization that, in theory, the Q-Collar works like a seat belt for the brain.

But Hussain and other experts expressed concerns over athletes overestimating the device’s ability to prevent concussions or more severe brain injuries — something that hasn’t been supported by research.

The FDA expressed its own concerns in October 2022, citing uncertainty about part of the study that led to the Q-Collar’s approval in a summary of its decision, The New York Times reports. The study emphasized the difference in brain tissue changes detected in scans for athletes wearing the collar versus those that weren’t, claiming those who did wear the collar had fewer changes. According to the New York Times, the FDA said the link between changes in study participants’ brain tissue and real brain injuries had yet to be “validated.”

Experts speaking with the outlet noted that while the idea of protecting the brain from inside the skull is worthwhile, studies supporting the Q-Collar’s effectiveness aren’t. They pointed to the data in the study as not making sense and that the scans are difficult to interpret, adding that few conclusions could be drawn based on the results. Even Q30 Innovations acknowledges additional research is needed to determine the benefits the collar can provide.

Still, you can expect to see athletes across multiple sports wearing the collars. Q30 lists numerous athletes that wear Q-Collars on its site, including Kansas City Chiefs linebacker Drue Tranquill, Baltimore Ravens tight end Charlie Kolar, and Buffalo Bills tight end Dalton Kincaid.