I'm so glad I bought this when I bought the backpack! I received these in about mid September, and I've flown multiple times since then. When wearing the backpack for any length of time--like when walking from long term parking to security, and then from security to my gate--using this sling bag as a waist belt properly adjusts the load. Once I'm at my gate and it's about time to load, I separate it and use this as a sling bag; I put it on like a belt, buckle in front, then spin it around so the buckle is in back and I have easy access to the pockets. (ID, keys, cards, AirPods, etc, are in there...) Once at my seat, I set the personal item (daily carry, that I use as a computer bag, mostly) on my seat, then I put the backpack up above as a carry on, and last I sit down and take off the sling bag, and strap it around the table tray, for easy access.

Once, I flew first class, which didn't have the table tray on the back of the seat in front of me--it was in the arm rest--so I simply lay the sling bag next to the personal item, under the seat.

I don't know if I would buy this if I didn't have the backpack, but I think I probably would. I strongly suggest that anyone who has the backpack get the waist belt/sling bag. Top quality, and very convenient. I hope to travel to Europe in the next 18 months, and I'm trying out these bags to see if they'll be worth using as my only bags as I travel internationally, and so far they're doing great. I'm sure they'll be the bags I…

Couldn't believe I would spend $100+ for this bag, but so worth it. Quality is superior and makes the plan ride so much more enjoyable not having to reach under the seat and dig around in a bag for the things you need inflight --- especially with the tight seating nowadays. With it attached to my waist, airline didn't even count it as part of my 2 carry-ons. Can't wait to discover all the other times/places I can put this to use.