The must-have accessory from New York Fashion Week costs just $4.

Round your neck, on your wrist, in your hair or tied nonchalantly around your [designer] bag, the “must-have” accessory dominating New York Fashion Week – both on and off the runway – sure is versatile.

Forget ugly shoes, necklaces that feel like you’re carrying a weight round your neck and anything fluffy.

This year it’s all about the white bandana.

No longer an accessory just for cowboys and/or gang members, it’s been spotted on everyone from designers and magazine editors to top models  and street style stars. Oh, and it costs just $4.

And there’s a very good reason for its ubiquity.

Started by fashion heavyweaight Imran Amed on his site Business of Fashion, the idea of wearing the accessory is “as a sign to the world that we believe in unity and inclusivity for all humankind.”

Called #TiedTogether, the idea is that you are either snapped wearing one or share a picture yourself with the hashtag, then donate to a relevant organisation promoting unity such as  the American Civil Liberties Union or the UN Refugee Agency.

Designers including Tommy Hilfiger, Diane von Furstenberg, Prabal Gurung, 3.1 Phillip Lim and Thakoon have or will be incorporating the bandana into their runway shows, while at the Calvin Klein show, front row guests were gifted one to wear to show their support.

“In fashion, visuals often speak louder than words. So join together this Fashion Month to make a simple and singular visual statement,” Amed wrote.

“Wear a white bandana as a sign to the world that you believe in the common bonds of humankind — regardless of race, sexuality, gender or religion.”

With New York Fashion Week just the start of a major fashion month across London, Paris and Milan, you can bet this will be one trend going worldwide.

Want to join in? You can buy a white bandana anywhere online, including this one we found for $4 from ASOS.

We’re obsessed with this Instagram account showing of fab and fierce “man-repelling” outfits.