This unisex sling bag from Bellroy is the reinvented fanny pack we've been waiting for - we recommend it for both its form and function

Let's get one thing straight here, Amir: Fanny packs are not "uncool," no matter what you say! I have probably seven or eight of them (yeah, people know me in the office as the girl with the fanny packs, it's fine), because they really are the most practical kind of bag, but they also look good.

Though I wouldn't wear this one around my waist because of it's size, it makes for the perfect cross-body sling bag. I can fit everything I'd need for a day out in the city or for traveling, all without weighing myself down much.

I really like that this one has a front pocket for holding essentials like my phone and lip balm, and another larger pocket for holding everything else. It's just the right amount of compartmentalization. The strap also compresses the bag down when I don't have much in it, or expands out when it's fully packed to make it feel customizable depending on my needs for the day.

— Sally Kaplan, Insider Picks editor

Aside from the expandable storage capacity, there are many other reasons we love the Sling.

Here's Insider Picks editor Sally Kaplan reaching into her Bellroy Sling Premium for a pair of sunglasses.

Backpacks are a smart option if you need to keep your arms free, but the Sling is even better because it's compact. When you need full mobility, you can move the Sling to the back with little effort. I find it's really convenient when I jump on a Citi Bike, but it's great for any number of scenarios.

Perfect for a grab-and-go lifestyle, the Sling goes can be worn just like any other shoulder bag.

You won't find any hard-to-open buckles here. This magnetic clasp is secure as ever, but easy to unfasten too.

This smaller interior pocket is an ideal spot for storing your sunglasses to keep them from getting scratched. You can also use it to stow smaller items that might get lost in the bottom of your bag.

At $99 or $159, the Sling and Sling Premium could cost you just as much as a full-size backpack, but you're not paying for storage capacity — it's the convenience and versatility. The design is compact but spacious enough for daily essentials you can't fit in your pockets. If you value mobility and comfort when on the go, this bag is for you.

Sally and I have different styles, but we both found the Sling easily blended into our wardrobes.

Aside from the extended leather panel on the premium version, there is no difference in size or usability between the two. If you have a smaller budget, I recommend the original version.