You want a slim bento box, not a lunch box.

The best lunch boxes for adults don’t look like lunch boxes at all—they’re slim bento containers that slide into a briefcase like a thin laptop.

I’ve been down this road. The products labeled “adult lunch box” are usually just overpriced mini coolers in fake leather. They’re thick, they’ve got a giant zipper, and they eat half the space in your bag.

Instead, get a flat, leakproof container. The Monbento MB Original is about two inches tall, looks like a little matte-black brick, and fits next to a 13-inch laptop. Bentgo makes a similar one with separated compartments, and that’s fine too. If you want zero plastic, a stainless steel tiffin works, but it’s round and can roll around—so only get it if you have a dedicated pocket.

Pair that with a thin insulated sleeve, or just throw in a reusable ice pack. You don’t need one of those zippered bags. A container with a tight lid and a cloth wrap is less bulky and looks more like a grown-up’s lunch.

Your lunch should be the most functional thing in your bag, not the loudest.