Ultraspire x UltraFlask 550 Hybrid Running Water Bottle - Ultra Squeezable, Soft and Comfortable, BPA and PVC Free, Made in The USA

I love this product even though I don't use the vest.First of all, it fits neatly in the side cargo pocket of my hiking shorts. It's so much more comfortable than a cylindrical bottle which either doesn't stay in a shallow pocket, or thumps annoyingly against my hip when clipped to a belt loop. The flask bottle works like a charm.The other amazing use is as my in-flight water bottle when traveling. This bottle slips neatly into the seat-back pocket in front of me and holds enough water for a long flight, but doesn't cause the seat pocket to stick out so far that it bangs me in the knees. It's also short enough that it doesn't prevent the tray table from lowering. This is totally my go-to travel bottle for flying.Great product. Lightweight and well made. The valve doesn't leak even if you sit on a full bottle.Maybe someday I'll take up running, but for now this bottle is the only one I'll use for flying or hiking

extremely light. never thought a bottle could be this light lol i don't use it for shorter races (half marathons). It's too hard to get out of the pack and secure quickly when you're racing for time. If you don't get it in tightly, i it can make the pack bounce and chafe your collar bone.I did read a review from an ultra runner who said this was the only bottle that didn't bruise her ribs. When you're running 30+ miles, that's definitely something to think about.it's perfect for hikes or really long runs where you don't mind stopping for a minute or so and don't want to carry a large bottle. very good quality, glad i bought it.

Use this bottle for my long runs and it holds a good amount of water/liquids. Love that i dont need a running belt, i can just fit it into the pocket of my leggings.

When this bottle arrived, it smelled like Costco, which is odd. (What is that smell? Pallets? Boxes? Plastic?) The smell went away in a couple of days, fortunately. This is absolutely my favorite reusable bottle: the flask shape means it doesn't fall out of my jacket or side pocket of backpack, I don't have to worry about accidentally dropping and breaking it, I can squeeze it so that when I'm running or hiking the water ends up in my mouth and not all over my face, and it doesn't impart a plastic taste or smell to the water. Also, I like the fact that it comes in lime green.

This is a "Goldilocks" bottle. I find soft flasks to be difficult to use, particularly when half-full, since they loose their form and sink into pockets/holders, etc. And, while hard plastic bottles may have their place, but, are not always comfortable in holders/pockets that bounce against the bottles.This is the perfect 'in between' item -- soft enough to be very comfortable in a chest/waist pocket, but, still retaining its basic shape. As an added bonus, you can suck out some air with each sip to eliminate water the sound of water sloshing.My absolute favorite flask bottle!

These are ok bottles in that they fit nicely into the vest. I have two main issues with them; 1) the nozzle is difficult to close properly, it wants to be smacked with some degree of force to close properly, lest it leak all over. And, 2) they are not 550ml as advertised. I could get it full to about 530 at the absolute most (to the very top of the bottle). If I blew into the bottle and tried to expand it some I could get a few more millimeters, but that was it.

I use 2 of these in my Zygos vest (awesome) for trail running. These are top notch. Very comfortable shape with great squeezability. Very positive closure on mouth pieces that are just the right hardness of rubber. I like the clear ones so I can see exactly what’s in there (and what’s going on in there). I use one for extra water and one for sports drink. Highly recommend!

Doesn't leak or drip -- sorta important, don't you think? And yet many water flasks I've bought do, and much more expensive ones! So that's good. As well, the bottle is soft enough that it conforms nicely in a chest-pocket style vest, which means less rubbing or bruising, AND easy to squeeze to get water out at higher volume that other flasks I've used.