The flexible bottle "Flux" is more convenient and upgraded. Easy to use shape like compact size hard bottles. It can stand on its own. When the bottle is empty, it can be folded like a soft flask, making it very lightweight and compact. Evolve into a bottle that you want to carry around. Comes with a spout cap for a more clean carry. Lock and unlock the dust cover by rotating it without touching the mouth. It is also easy to hold, easy to put in and take out, and has a larger bail handle.