Khalil Mack will likely lose his appeal to wear an unorthodox facemask.

The Raiders’ rookie outside linebacker wore a specially-designed protector in college arranged to prevent offensive linemen from poking him through open portions of his facemask, but, according to the NFL Network, those designs will be banned for the upcoming season.

That will also impact Raiders defensive end Justin Tuck, who wore an identical design he called a “Shredder Mask” -- named after the popular arch-villain in the Teenage Mutant Ninja Turtles comic -- after appealing for the rare design to the league office years ago.

New facemask guidelines were outlined in a memo obtained by NFL Network reporter Ian Rapoport on Monday afternoon.