NASCAR created quite a social media stir as reporters started sharing new the safety rule updates, making different items like a head sock/helmet skirt, underwear and socks a requirement instead of a recommendation.
The key context here: a fire-resistant head sock/helmet skirt, underwear and socks. Specific SFI or FIA-rated gear will be required, falling in-line with other series. It remains unknown at this time how this will be checked.
NASCAR is not the first to make this move. The FIA clamped down on Formula One last spring when jewelry and underwear checks were made part of the scrutineering submission to make drivers comply with the International Sporting Code regulations.