Below you can find the Modern nfl helmets have chin straps that identify head injuries; back in the '20s helmets were made of this material Jeopardy Words Answer. The answer to Modern nfl helmets have chin straps that identify head injuries; back in the '20s helmets were made of this material has 7 letters. This clue belongs to the Back in the day category and is part of Jeopardy Word Level 2191. If you scroll near the bottom you will find other clues and answers part of level 2191