It is rare that I come across a product that is this perfect. Tatonka usually do a fine job but here, they have excelled themselves.
I bought this bag when I was moving from Germany to Ireland. I knew that I would be flying back forth and that I would have a lot to carry. Also, airlines are getting more strict about carry on bag sizes and weights. I wanted something that would just avoid breaking the limits on size and that would be tough enough to handle abuse and yet light enough to give me maximum flexibility and that is just what I found.
You can configure the bag as a normal case that you carry in one hand. There are then no rucksack straps and no sign that it has another mode. Then by unzipping a cover flap, you can convert it into a rucksack in an instant. Typically, I will travel to an airport with the bag in rucksack mode and then take a moment to convert it to hand-held case mode before checking in. I can then carry it on to the aircraft and stow it in the overhead without worrying about rucksack straps getting caught and tangled. It fits perfectly and if needed, it can also fit under a standard aircraft seat. On arrival, converting it back to rucksack mode is so quick and discrete that I usually do this while standing in the aisle of the aeroplane waiting for the doors to be opened.
I have been all over the place with this bag and it has never let me down. The zips and fasteners are the best that I have ever seen and it works well with heavy loads. I can go to my corner shop and buy a twenty kilo bag of coal. The bag is big enough to take it, and strong and comfortable enough that I never have any doubts that I can carry it.