FILE – In this Sept. 11, 2017, file photo, a VICIS Zero1 helmet is displayed in New York. The NFL for the first time is prohibiting certain helmets from being worn by players.
In notifying the 32 teams Monday, April 16, 2018, the league has sought to have players stop using 10 helmet varieties. Laboratory testing showed that the VICIS Zero 1 models of 2017 and 2018 rate best for player safety. (AP Photo/Mark Lennihan, File)