TEMPE, Ariz. -- Almost everywhere Arizona Cardinals coach Bruce Arians goes, he's wearing one of his signature driving caps.

Except on the sideline.

Arians lobbied the NFL to let him wear his hats in 2013 before his first season with the Cardinals. His request was denied even though they're made by New Era, the league's headwear partner.

NFL spokesman Brian McCarthy said league-wide consistency was behind the NFL's decision.

"All sideline personnel throughout the league wear similar apparel," McCarthy said.

Arians may not be able to wear his driving caps -- that come in red, white or black -- on the sideline. But at the news conference after the game? Arians changes from his sideline baseball-style cap to his signature look.

When Arians was initially hired by the Cardinals in 2013, he wore a similar style hat made by Kangol. He approached New Era about designing a hat he could wear to team functions, such as news conferences, and the result is what Arians dons daily.

Hats have always been a part of Arians' life, he said.

"I think just growing up in the north we always wore hats, and different style hats," Arians said. "So it was one that (New Era) ended up with ... a pretty cool one, so I liked it."

The driving cap isn't just a fashion statement or a way to keep his bald head warm. They have become a walking billboard to raise awareness and money for the Arians Family Foundation, which supports CASA of Arizona (Court Appointed Special Advocates). Arians' wife, Christine, worked as a CASA for years.

There's not an occasion too fancy for Arians' hat. He wore a black one with his initials embroidered on the side during Monday night's Arians Family Foundation Fundraiser Dinner at a steakhouse in Phoenix.