This article has been corrected from the version which appeared in print editions of the Inquirer, and prior to that, the Daily News.

There is no piece of equipment which can prevent concussions. Items such as Unequal's headband can only attemtpt to reduce the risk of suffering brain trauma.

ASTM International, which is a nonprofit organization, does not allow companies to make substantiated claims that they reduce the risk of brain trauma. It also does not test or certify other sports equipment.

VANCOUVER, British Columbia - The black headband that U.S. defender Ali Krieger has been wearing at the Women's World Cup isn't a fashion statement. Unequal Technologies, based in Glen Mills, Delaware County, developed the headband to reduce the risk of suffering concussions.

And while there is no science showing that headbands prevent or reduce the risk of concussions, Krieger is one of several World Cup players who are wearing them in this year's tournament.

"If I get hit one more time, it could be the end of my career," Krieger says. "I need to be prepared and wear it and suck it up and throw my pride to the side and be safe about it, because I want to continue to play."

Delran native Carli Lloyd also has worn the headband this year, though not at the World Cup.

Nothing can eliminate all instances of brain trauma in sports. And there is scant evidence that these types of headbands prevent or reduce the risk of concussions, says Anthony Kontos, research director for the UPMC sports medicine concussion program in Pittsburgh,

"There really aren't any good data with humans that show this is going to prevent concussions or anything like that," Kontos said.

Rob Vito, who also teaches in Penn State's Master of Business Administration program, founded Unequal in 2008 and is the company's CEO. Unequal's first major foray into sports came in October 2010, when it designed a chest protector for then-Eagles quarterback Michael Vick. Since then, it has worked with Dallas Cowboys quarterback Tony Romo, former Pittsburgh Steelers safety Ryan Clark, and Steelers linebacker James Harrison.

The company also has worked with lacrosse, baseball, and other sports.

In soccer games, brain injuries aren't just caused by head-to-head collisions. They're also caused by contact between a player's head and a ball, the ground, or other objects, such as a goalpost.

Unequal claims to combat such collisions with two materials it has created. The first is a Kevlar-like fabric called TriDur, which gets heat-sealed to a high-density foam called Airilon and encased in a moisture-wicking outer layer.

When a ball or anything else hits the headband, the energy from that contact is dispersed across the headband. Without the headband, that energy is concentrated at the point of impact, according to Unequal.

In a study published this year, the UPMC's Kontos and colleagues found that a different brand of headband did not appear to protect players from what he called "subtle" cognitive impacts of heading a soccer ball. In the study, published in "Research in Sports Medicine," participants who did not wear the headbands fared about as well as those who did.

As for sharper impacts, such as head-to-head or knee-to-head, there are no quality randomized trials that indicate headbands are helpful, Kontos said.

Krieger started wearing Unequal's headband after she suffered a concussion during a National Women's Soccer League game in April. Before the former Penn State star returned for the U.S. team's three World Cup warmup games, national team assistant coach Steve Swanson reached out to Unequal to try the headband.

Only in the last year or so has the rest of the world started to catch up to America's understanding of brain trauma in soccer.

The 2014 Men's World Cup offered a prime example. Germany midfielder Christoph Kramer suffered a concussion during the championship game against Argentina. The international television broadcast showed him appearing to lose consciousness, but the German team's medical staff let him keep playing.

Fifteen minutes later, still showing clear signs of being dazed, Kramer finally was removed from the game.

ESPN analyst Taylor Twellman, a former U.S. national team player and New England Revolution forward whose career ended prematurely because of concussions, criticized FIFA and the German federation. So did many of Twellman's colleagues, including those from other countries.

But beyond ESPN's reach, there wasn't the same level of reaction in the moment. Only in the days afterward, as American reporting circulated globally, did international opinion begin to turn.

This summer, several teams at the Women's World Cup are using Unequal's gear. In addition to Krieger, players from Mexico, Ecuador, New Zealand, and other nations are wearing the headband.

After the headband was judged to meet the ASTM's standards, it had to pass one more test: a player's opinion of how it affects the ball's movement.

That can be just as rigorous a challenge. Make the material too hard, and the ball will ricochet across the field. Make it too soft, and the ball will fall straight down.

So far at the World Cup, there doesn't seem to be much difference in how the ball comes off a header compared to a player not wearing the headband.

The headband, which weighs 6 ounces, is not just for world-class athletes. It's available on the company's website and through other retailers for $39.95. There's also a smaller, lighter version for $29.95.