I just became of aware of these innovative Vapur drink bottles which can be rolled, folded or flattened when empty – and easily tucked away! We use reusable bottles but somehow, once they are empty, I just hate carrying them around. It’s not rigid so can fit easily into most places and is also reusable, attachable, freezable, identifiable, washable, and BPA-free – sounds like a dream to me, especially for air travel!