This works very well for us - folds flat to go in rucksack, opens up to good size feeding or drinking bowl. I can understand it wouldn't work if your dog is likely to bite it, but it works so well for us that I will be buying another and have recommended it to friends.
This bowl lasted for 3 outings. My puppy labrador picked it up after drinking, her puppy teeth went straight through it and the rim separated from the bowl. In future I will be using one of my stainless steel bowls.