21” size – UPDATED REVIEW I have been traveling with this bag for 9 months now and have run this bag through 18 flights to-date. I will try to answer as many questions as I can in this review. I just measured my bag: Exterior dimensions of the “21 inch” bag: 22 x 15 x 8" INCLUDING THE WHEELS and hand handle with the telescoping handle folded in. Internal packing area: 15.5 x 13.5 x 6.0". This can be increased to 15.5x13.5x7.0. by unzippering the center zipper. G, which is a good idea for road travel but not a good idea for flying. If you fly a large jetliner, it makes no difference. If, however, you are flying a regional jet, they have a depth limit of 9". It is easy to stuff your bag in such a way that the soft side presses out more than 9". If you don't extend your case, it is easy to squish the side to make it fit, but if you have extended the case to 9" and then overstuff it, the bag will wind up checked on those "RJ" jets. Will it fit overhead?: Most aircraft? - Yes. Small regional jets?- Actually it will but they may make you gate check it anyway. Will this fit under the seat: Usually not. The outer pocket is good for items up to 13.5 x 12.5 x 1". The pocket is actually 15" high but because of the zipper placement, I call the useful pocket height 13.5" There has been a lot of speculation in the reviews as to how much this case can hold and how durable it will be in the long run. The durability of the canvas-like cloth exterior has been excellent and it wipes clean when the airlines are abusive. In the 9 months that I have owned this bag, it has been on 18 flights; some as carry on and a few as checked luggage. It has been to the Mountains of Montana, the remote southern deserts, and the "wilds" of Las Vegas. Despite the wobbliness of the handle, it holds up very well and is easy to operate. I am careful to pack right and I've never had a tip-over issue. The wheels have worked well on tile, linoleum, carpet, concrete, asphalt, dirt, and snow. My typical load is 5 days' worth of clothes, toiletries, and "paperwork," plus a large (weekly planner type). And, I have never opened the expansion section. Isn't 15.5 x 13.5 x 6.0" rather small? Well, that depends on how and what you pack. If you lay your clothes in and load as you go, then yes, this is a small bag. However, if you pack like me (roll everything up then pack it, then hang your clothes up on the other end) this bag is all you need. On a trip a few weeks ago, I packed 6 days-worth of clothes, including a suit and a change of shoes, into the main compartment without extending it. I put my 3-1-1 (toiletry bag) in the side pocket with my itinerary and placed this bag in the overhead. Without the suitcoat, I could have gotten a laptop in there too. As was, I was able to carry a "pad" and a few small souvenirs or snacks in the side pouch. If you carry curlers or a blow dryer, though, you will only get 2-3 days-worth in there. Also, pack evenly or the bag may be off balance when standing. Empty weight: 5.5 pounds Length from wheels to top of extended handles: 42” Outside pockets: 1 (the other zipper is to expand the capacity) Are the wheels removable? No Will a laptop fit in the front pocket?: No, but an iPad will. How many total wheels? 4 Can I use a TSA padlock?: Yes