PITTSBURGH -- Pittsburgh Steelers linebacker James Harrison didn't want to wait for the NFL to do something about protecting his head, so the four-time Pro Bowler decided to do it himself.

After enduring what he estimated as "double digit" bouts with concussion-like symptoms throughout his decade-long career, Harrison began using a special layer of padding inside his helmet last fall and is pleased with the results.

"I haven't seen any spots or had any blackouts," Harrison said Tuesday.

Harrison was the first NFL player to use the CRT padding developed by Unequal Technologies inside his helmet. Philadelphia Eagles quarterback Michael Vick began using a flak jacket lined with military-grade Kevlar during the 2010 season, but Harrison was the first player to put the quarter-inch padding in his helmet.

He's been joined by around 100 players over the last 12 months and feels the extra weight (about 3-4 ounces) is worth the feeling of safety it provides.

"To protect my head I'd take a pound more," Harrison said.

The outspoken 2009 NFL Defensive Player of the Year believes the movement could catch on. One of the NFL's fiercest hitters, Harrison says he played through concussion-like symptoms in the past but as he's aged has become more wary of the long-lasting impact repeated head shots can have on a player's future health.

"If something works, I'm going to use it," he said.