San Francisco 49ers star Nick Bosa made waves post-game on Sunday at Levi's Stadium as he crashed quarterback Brock Purdy's interview while wearing a "Make America Great Again" hat. 

But that move from Bosa could result in a fine from the NFL.

The NFL rulebook states in Rule 5, Section 4, Article 8 what players are allowed to wear, and more importantly, what they are not allowed to when they get to the stadium on game day. 

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Nick Bosa vs Cardinals

San Francisco 49ers defensive lineman Nick Bosa after the game against the Arizona Cardinals at Levi's Stadium in Santa Clara, California, on Oct. 6, 2024. (Kelley L Cox-Imagn Images)

"Throughout the period on game day that a player is visible to the stadium and television audience (including in pregame warm-ups, in the bench area, and during postgame interviews in the locker room or on the field), players are prohibited from wearing, displaying, or otherwise conveying personal messages either in writing or illustration, unless such message has been approved in advance by the League office," the handbook states.

Now, the rule breaks down that such things as "anniversaries or memorable events, or to honor or commemorate individuals" with helmet decals, jersey patches and arm bands are allowed as long as the league office is notified. 

However, when it comes to political messaging, this rule is very clear. 

49ERS' NICK BOSA GETS SUPPORT FROM NFL GREAT AFTER FLASHING MAGA HAT

"The League will not grant permission for any club or player to wear, display, or otherwise convey messages, through helmet decals, arm bands, jersey patches, mouthpieces, or other items affixed to game uniforms or equipment, which relate to political activities or causes, other non-football events, causes or campaigns, or charitable causes or campaigns. Further, any such approved items must be modest in size, tasteful, non-commercial, and non-controversial; must not be worn for more than one football season."

The league does, however, allow players and coaches to discuss politics during press conferences. 

Nick Bosa runs out

San Francisco 49ers defensive end Nick Bosa is introduced before the game against the Kansas City Chiefs at Levi's Stadium on Oct. 20, 2024. (Cary Edmondson-Imagn Images)

However, when posed with the question about the hat, Bosa said he was "not gonna talk too much about it, but I think it’s an important time."

The NFL did not immediately answer a request for comment from Fox News Digital.

How much exactly could Bosa get fined? 

The league dished out a $10,000 fine to Pittsburgh Steelers receiver George Pickens for displaying a personal message on his eye black during "Sunday Night Football" against the Cowboys. 

Bosa received flak for displaying his MAGA hat, but there were others that showed support for him, including NFL Hall of Famer Brian Urlacher. 

Urlacher commented under Bosa’s Instagram post, where the star lineman had a collage of photos that included the moment he showed his Trump support with the MAGA hat. 

Nick Bosa

Nick Bosa of the San Francisco 49ers stands on the field in the third quarter against the Kansas City Chiefs at Levi's Stadium on Oct. 23, 2022. (Ezra Shaw/Getty Images)

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"MAGA," Urlacher wrote with two American flags. 

Bosa finished with one sack on Sunday night to notch 4.5 on the year. 

Fox News' Ryan Gaydos contributed to this report.

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