Two stars because our mouthpiece was constantly leaking! I have another hydration pack from another company that has a mouth cap, and not just because it didn't have one, but because the water kept leaking out and we literally had to tie our mouthpiece up in a vertical position to prevent that water escapes. on all our arms and legs. On the third day of our trip we just had to throw this aside and use my good backpack. We sent it straight home! And it's not waterproof at all!