Harrison: I've had "double-digit" concussions updated 2:42 p.m. PITTSBURGH (AP) - 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 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. The green padding uses material developed to protect combat military personnel. The padding square packs that can be cut into different shapes then stuck inside helmets from various sports, including hockey and baseball. Harrison became aware of the product while looking for a little extra protection after fracturing his right orbital bone last season. Pittsburgh backup quarterback Charlie Batch, a member of the NFL Players Association's executive council, introduced CRT to player representatives from around the league, which quickly helped expand usage. Unequal Technologies president Robert Vito said the product doesn't claim to prevent concussions but that anecdotal evidence from players from all levels seem to indicate the material can help minimize the recurrence of concussions. Harrison noted the NFL has gone to great lengths to address concussions and hand out "crazy fines" to players who make illegal hits but haven't taken aggressive action in trying to update the equipment. "The league is mandating next year that we wear thigh and knee pads," Harrison said. I don't know how many people's career has been ended on a thigh or knee bruise. We have guys now that are 30, 31 years old that are having to quit the game because they have severe headaches ... I think you should be focusing more on (the helmet) than knee or thigh pads.