Guardian Cap

[StlCards]

the only rule I could really find was this.

ART. 1 . . . Mandatory equipment. Each player shall participate while wearing the following pieces of properly fitted equipment, which shall be professionally manufactured and not altered to decrease protection:

a. Helmet and Facemask:

1. A helmet and face mask which met the NOCSAE test standard at the time of manufacture. The face mask shall have a surface covered with resilient material designed to prevent chipping, burrs or abrasiveness and be properly secured to the helmet as designed by the manufacturer.

2. The helmet shall be secured by a properly fastened chin strap with at least four attachment points.

NOTE: All players shall wear helmets that carry a warning label regarding the risk of injury and a manufacturer's or reconditioner's certification indicating satisfaction of NOCSAE test standards. All such reconditioned helmets shall show recertification to indicate satisfaction with the NOCSAE test standard. The coach's pregame verification to the referee and umpire that all players are properly equipped in compliance with the rules includes the exterior warning label.

Doesn't really seem to violate this. I would consider it an alteration to the helmet, but I don't think it would decrease protection.