Sisters Este, Danielle, and Alana Haim (ages 28, 25, 22) of the self-titled indie power-pop trio each has her own style, though like a chord, it’s how the three work together that’s so striking. And at a concert on Monday night,the girls brought their brand of West Coast effortless-cool to Brooklyn, N.Y. to kick off the “Live in Levi’s,” the latest campaign by the iconic denim label.

“It’s taken many hours to figure it out—there have been some very gross outfits that I hope never resurface—but we definitely each have a stage uniform,” said Alana, the youngest, who moved from drums to guitar to keyboard wearing a pair of vintage Levi’s orange-tab cutoffs she scored at a flea market. Danielle, the lead guitarist and vocalist who favors tomboy-chic blouses and ’70s-inspired silhouettes, opted for vintage 501s. “Whenever our Mom sees holes in clothing she’s like, ‘Give it to Goodwill’!” laughed Este, who rescued her high school jean jacket from a give-away bag.

As for off-stage fashion? “It’s all the same. We’re most confident when we’re comfortable, we like feeling as though we’re just jamming in the living room back in L.A.” And as the girls talked about childhood Play-Doh obsessions, koogle, and snacked on Snickers bars in between songs from their album, Days Are Gone, the crowd of 1,700 indigo-clad fans felt like they were at right at home, too.

Plus, find out how to wear denim to work with our ultimate jeans guide!