We Just Tried 13 CSB Best Sellers, From Hailey's Favorite Tank to the Leggings NYC It Girls Swear By

Some things in your wardrobe you simply don't mess with. Denim is probably at the top of the list, and activewear isn't far behind. Once you find the right style or brand, it's hard to imagine looking anywhere else. All that said, I've taken it upon myself to convince anyone reading this to step outside their comfort zone and try CSB activewear if you haven't. Trust me, it'll be worth the time, the money, and the slight discomfort of trying something different.

Founded in 2019 by Rachel Dillon, Australian activewear label CSB has grown from a trio of crop tops into a viral favorite among A-listers, editors, and stylists. Hailey Bieber helped bring the brand into the spotlight when she wore its Form Leisure Tank in chocolate brown to Coachella in April, and has since been spotted in other everyday styles. Alix Earle is also among CSB's fan base.

What's behind the buzz? CSB strikes an increasingly coveted balance between fashion and function. Its collections pair an aesthetic-driven look with performance-minded design, without venturing into technical territory. The fabrics are incredibly soft and barely there, offering support while allowing for easy movement. The pieces keep up with your everyday routine, too, so you don't necessarily need to change out of them when you're going from yoga to brunch with friends.

Celebrity sightings and internet discourse can only reveal so much, though. To see whether CSB lives up to the hype, I enlisted two fellow Who What Wear editors, each with a different body shape and lifestyle, to put the brand to the test. Together, we wore the pieces around New York City—from coffee meetings and Sunday errands to Pilates classes and weightlifting sessions. Read on for our honest reviews and to see how we styled our favorite items.

Who What Wear Editor Reviews

Ana's Review

I’m pretty particular about my activewear, especially since I spend a good amount of time in workout clothes, whether I’m heading to a class, going on a walk, or simply running errands. After trying a few pieces from CSB, I can definitely see the appeal. The designs are flattering, the pieces feel well-made, and everything has that sleek, put-together look that makes you feel a little more motivated to work out.

The first thing I noticed was just how compressive everything was. The fabric really holds you in, which I can appreciate, especially when it comes to leggings and these matching top and bra sets. I could see myself reaching for these pieces for lower-impact workouts like Pilates, barre, or even a lighter gym session. They feel supportive and structured rather than super soft or barely there, so I think it ultimately comes down to what you prefer in your activewear.

My biggest note, though, is definitely the sizing. I’m typically a size 12 or large in most brands, but with CSB, I actually had to size up to an XXL in both the tops and leggings to get a fit I felt comfortable moving around in. I don’t necessarily mind sizing up, but it was a pretty significant difference from what I’m used to, and I think it’s worth knowing before ordering.

CSB on Ana

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Nikki's Review

It took just one tank top to turn me into a fan of CSB: the Form Leisure Tank Top, to be exact. I got it back in March and haven't stopped talking about it ever since. While it took a little more effort than usual to pull it over my head—possibly because it was a size too small—once I had it on, I knew the effort was worth it. It hugged me in all the right places. Plus, when I wore it to Pilates, it provided consistent support—even in downward dog and plank positions.

Since early 2026, I've had the chance to try the brand's sports bras, bike shorts, leggings, halterneck tops, and flared pants. Each piece offers a different silhouette, yet they share a consistent fit that's flattering and comfortable. You can tell Dillon understands how women want to feel in activewear—confident, supported, and stylish. What I particularly love is that every collection is designed with a fashion eye. Nothing feels overly technical or sporty; instead, everything is chic and polished. The pieces also integrate easily into my wardrobe. Beyond pairing them with sneakers and a sweatshirt or zip-up jacket, I love styling the leggings with loafers and ballet flats, and wearing the long-sleeve tops and tanks with trench coats and leather jackets. If I've inspired you to try the brand, be sure to size up one or two sizes for the most comfortable fit.

CSB on Nikki

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Sierra's Review

"I’ve been seeing CSB everywhere lately, especially at the more high-end Pilates studios here in New York. On my recent trip to L.A., I was finally convinced to give the brand a try. I went on a lot of hikes, and most of the more stylish women I saw were wearing the brand. My first impression is that the pieces are cut really well, both in a flattering and fashion-forward way. Everything feels classic, like a wardrobe staple, but the cut makes it feel a little more polished. They are also a step ahead of the trends which is refreshing to see because I’ve been loving a flared legging lately, for example, and the brand has so many versions of it. Its leggings and tops have a more fashion-forward cut than most activewear, and it does color-blocking really well. I’ve already added a few more items to my wish list because this first experience was a good one."

CSB on Sierra

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