GSI Outdoors  Boulder Flask - 10 fl. oz.

I got this flask for two reasons, one I don’t like hauling a huge water bottle all the time and I bought a new waterfly sling bag and my Sigg bottle was too big so I thought, ah, a smaller bottle, a better shape, and went ahead and bought this. Fits the outside carrying pocket perfectly. As a birder our birding group has a tradition where you take a shot when you see a new lifer (first time in your life seeing a particular bird). Again, needed a flask that was compact enough that I could haul it easily and this one will do the trick. Solidly made, easy to clean, you’ll like this bottle for all the right reasons.

On short hikes with my dog I have been carrying a water bottle and collapsible bowl in a small "freebie" back pack. Bought this so that I can dispense with all that. Lightweight and fits in my back pocket and I clip the bowl to a belt loop. Worked so well that I am purchasing a second one so I can carry two. Lighter in weight and more capacity than other offerings made of stainless.

I bought this to take with me on long urban walks and tuck into the small crossbody bag that I carry. It is working perfectly, so spills, fits well, so convenient!!

It's a plastic flask not much more than that. Oh, the rubber trim was peeling the first day.

This flask is compact, cleverly designed, and well made. Most importantly for me, it fits perfectly in the little Bellroy Venture Ready 2.5L sling while still leaving room for my other gear. The only downside is that some people will assume I'm drinking alcohol. I'm pretty sure water molecules don't mind being in a bottle that's rectangular rather than tubular, people.

As advertised and would definitely recommend to anyone needing a rugged, reliable way to transport spirits. The only reason for 4-out-of-5 stars is the cap. Once closed, it seals well and I'm never worried it will accidently open. Once open however, it is a little difficult to line up the threads of the cap with the flask one-handed. It's not impossible, but I find myself worrying about cross-threading and not completely sealing the flask if I can't use both hands to replace the cap.

There’s no shortage of water bottles for sale and you probably already have your fair share, so do I really need another? Possibly yes. This one is well made and should last for some time. What sets this one aside from others is its convenient shape. It fits in my front pocket, and for those times when you aren’t required to bring a a lot of water, this one fits the bill.

I’ve been asked to review this flask which I never received. I ordered with an REI discount coupon, but later got a message that they weren’t shipping it because it was out of stock. I repeatedly signed up for email notifications when it was back in stock, but each time I reordered it, I got the message that it was out of stock. So I give up

The Boulder 10 flask met all the criteria I was looking for in a durable, portable, and transparent flask. The only thing I would improve is the cap. I was looking for a flask with a cap that I couldn't lose, which the Boulder has, but I have had other flasks with attached caps that were easier to close.

I like the lightweight flask as it's easy to fit in any nook and cranky in my pack and paniers. It's easy to fill and see the level since it's clear plastic. The top is a lit5le hard to flip open, so I have to lift it up to open it fully.