<P> Riddell Revolution helmets are a line of football helmets . The helmet brand is the most popular model in use in the National Football League, used by 83% of the players in the league as of 2008 . The most recent model in the Revolution line is the Speedflex helmet . This model can come equipped with Riddell's HITS Technology, which consists of a sensor in the helmet that relays data regarding the severity of each hit to a computer system . The Speedflex also features a built - in hinged panel located on the front near the top . In head - on collisions, this panel gives by up to a quarter of an inch (6 mm), helping to absorb the impact . </P> <P> The Revolution helmet was conceived in an attempt to reduce the risk of head injuries such as concussions . What research has been done on the helmet's efficacy so far has been inconclusive . </P>

When did the riddell speed flex come out