The bags themselves range from traditional—the typical polyester pouch with a horizontal zipper running across the face—to looking more like a luxury handbag with a belt strap. The prices are just as varied. Adidas’s branded polyester waist bag is $25, while Gucci’s metalassé-stitch leather belt bag costs $1,100 and Louis Vuitton’s monogrammed “Bumbag” in coated canvas will set buyers back $1,500.

They’re also proving able to draw customers of different genders. The bags were noticeably prominent on the women’s spring 2018 runways, for instance, but they’ve also been a major trend for men, who tend to wear them slung over the shoulder and across the chest, rather than around the waist, avoiding the unsightly bulge the pack can create. (“Looks like your belt is digesting a small animal,” Jerry Seinfeld’s character on Seinfeld said once to a fanny-pack-wearing George Costanza.)

“Fanny packs, or ‘waist bags’ as we now call them, are the fastest-growing segment in the men’s accessories market,” Marshal Cohen, an analyst with market research firm NPD Group, told the Wall Street Journal (paywall) in November. According to NPD data reported by the Journal, from September 2016 to September 2017, sales of the bags grew more than 10% to hit $100 million.

The bags fit into a broader embrace of practical, versatile items happening at the moment, and they also tie in with fashion’s recent zeal to elevate all that was once considered ugly. They’ve gotten a boost in cachet from celebrities such as Rihanna and the rapper A$AP Rocky.

The rise of streetwear, which has featured the bags in the past, may also be helping their cause. One notably hyped fashion accessory of the last couple years is the fanny pack Louis Vuitton created in collaboration with the streetwear label Supreme. On the runway, models wore them dangling across their bodies, of course, not at their waists.

A model wears a creation for Louis Vuitton Men's Fall Winter 2017-2018 fashion collection presented in Paris, Thursday, Jan.19, 2017. (AP Photo/Francois Mori)
He’s wearing his fanny pack all wrong.
Image: AP Photo/Francois Mori

📬 Sign up for the Daily Brief

Our free, fast, and fun briefing on the global economy, delivered every weekday morning.