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Designed to complement the brand's suitcases, the duffel is the same width as the suitcase, and it has a trolley sleeve to secure it your telescopic handle.

Frequent (and semi-frequent) travelers know that there's a fine line between intelligent packing and overpacking. When you've packed well, you have everything you need (and then some) with room to spare. When you've overpacked, you only end up wearing half of what you brought and you can't even squeeze a souvenir inside for your friends and family back home. After plenty of testing, though, I've determined the best way to perfect the packing formula is to consistently travel with the same two bags: a personal item and a carry-on (unless a longer trip requires bigger luggage).

That being said, using mismatched bags — carrying a personal item that doesn't complement your carry-on — can cause plenty of headaches. If your personal item is the backpack you've owned since college, it surely doesn't have a trolley sleeve, and it probably can't stand on its own on top of your suitcase. There also probably isn't enough room for all of the items you don't want jostling around inside your suitcase: your laptop, headphones, chargers and other (delicate) technology.

That's why if you have a Monos suitcase, for example, which we previously determined were better bags than Away's, you should get a bag from Monos to go with it. And now you can. Monos's revamped Metro Collection features a backpack and a duffel specifically designed go with the brand's Carry-On and Check-In suitcases.

Both of the bags, which are partially made from repurposed PET (and 100 percent vegan), boast plenty of internal storage solutions, but it's the duffel that proves most useful. It's big enough to fit a few rolled up garments, a 15 inch laptop, a water bottle and other tech, like an iPad and a camera. (How about a disposable one?) It's small enough, however, to fit perfectly atop the suitcase's lid, slipped over the handle using its convertible trolley sleeve. When carried separately, the sleeve can be zipped shut and used as a pocket.

You can also carry the bag with or without its external pockets, the Metro Classic or Folio Kit, depending on how much it is you need to tow. They both can be attached using the brand's QuickSnap system, a modular section on the exterior of the bag that connects to other kits using magnets.

Altogether, it's a tidy system that perfectly complements the brand's suitcases, which were tidy to begin with. As seen above, they work well together and make getting from Gate A to Gate D or your front door to your Uber, well, easier, because when your backpack spills out over the corner of your suitcase, it can make it difficult to drive.