Review on Hydrapak UltraFlask Collapsible Soft Water Bottle For Hydration Pack by Joshua Ngo

First time using a "collapsible” bottle; how does it collapse again? Maybe I’m not doing it right, but the bottle just seems to sag into a shapeless blob and doesn’t exactly collapse as I think that word means. Use it in left pocket of a 3L vest; bought an extended straw but that ended up smacking me in the face whenever I move LOL. The normal cap and bite valve worked well, altho I found the valve to be a bit sensitive to the slightest squeeze. Anyways, can appreciate using this as opposed to filling up a toss bottle