A Spirit Airlines passenger who wore an American flag-themed neck gaiter as a mask got into an altercation with a flight attendant when he refused to switch the gaiter that the flight attendant said was “not legal.”

In the video posted to Twitter, the man repeatedly asks the attendant for the Centers for Disease Control and Prevention (CDC) guidelines about the use of gaiters as face coverings.

“I don’t have to wear the mask that you gave me,” the passenger said, according to the video. “I’m wearing the mask that I have…I’ve been on 20 flights with this same exact mask.”

Before the flight attendant walked away, he told the passenger that the airline would “have the authorities waiting for you when you land.”

It was unclear if that ended up being the case, but the exchange, which was recorded by the passenger, forced the airline to respond to the confrontation.

“Safety is Spirit’s number one priority, which is why our face covering policy adheres to CDC guidelines,” the airline said in a statement.

“The CDC cautions that gaiters may not be effective, which is why we require Guests to either double up neck gaiters so they’re dual-layered and hug the chin, or to switch to a standard ear-loop face covering.”

Spirit Airlines said the passenger declined to double up his neck gaiter or wear another mask. The airline also denied that the man was targeted because of the American flag design on his gaiter.

According to the company website, passengers must wear a proper mask “while at the airport, on the jet bridge and onboard the aircraft” and can only be taken off to eat, take medication, or drink.

Open-chin triangle bandanas, face coverings containing mesh or valve material, and face shields are not approved as proper masks, according to the airline. However, a face shield can be worn in addition to a mask.

“Guests who choose not to comply with our face covering requirement will lose future flight privileges with Spirit,” the website says.