UltraFlask Speed (500ml or 600ml) - Collapsible Soft Flask Water Bottle for Hydration Vests and Running Packs with Easy Open Cap

It’s solid and the best ones on the market. I have zero idea how I can even complain about it but it does exactly as advertised and don’t notice anything wrong with them. Bought them for my outdoor vitals skyline 30 since I lost one due to tsa. But for what it is I love them. I don’t have any leaks, stores flawless in several running vest I own and two different backpacks, it’s easy to carry and no funky taste and they are easy to clean so I don’t mind putting in some tablets in them even if trailrunning a two day trip. Plus I love the straws so it’s right by my face so I don’t even need to reach and drink instead I just turn my head and bite the valve and drink. It’s just all around a good design

Great addition to son's collection and they were used in the cocodona 250. Perfect size, sturdy product and worked well for the race.

These UltraFlask Speed bottles are excellent for trail running and longer training sessions. They fit perfectly into most running vest pockets, and the soft design means they conform to your body without bouncing or poking like traditional hard bottles. The bite valve works smoothly with a good flow rate, and the extended straw makes it easy to sip without removing the bottle from the vest — great when you don’t want to break stride. I also appreciate that the straw can be removed if you prefer a lower profile setup. As you drink, the bottle compresses to reduce sloshing and becomes lighter, which is especially helpful later into a run. They’re also simple to clean and dry, and the wide opening makes adding ice or electrolytes easy. Durable, lightweight, and very comfortable to carry — highly recommended for anyone running with a hydration vest or needing compact hydration on the go.

A very good flask that does not leak.

One race in, and I'm in love. I have that common salomon vest, and had to replace the hydrapaks. These are bigger than what I had but still fit. Running with the straws was a mixed bag - I'm still working on the best way to keep them from bouncing around while also not being pressured to my neck. The access for a quick drinky drink was amazing. These also feel thicker than the Salomon version that came with my vest. These are worth the upgrade - though, I haven't tried other brands for a true comparison.

Purchased these for use in a 40 mile trail ultra. I had no leaks and no issue during the entire event. I put them in my Salomon adv skin 12, they were a little tight fit just fine. I was able to bend the straw and use the retention straps on the skin 12 vest. If you do use them in a vest I found I the straws flapped if I didnt make sure the slightly firm oval tops of the bottles weren't all the way down in my vest. As soon as I made sure to push them down so the firm top was below the elastic, they held firm and weren't hitting me in the face. I found that screwing the tops off and on to not be as smooth as the flasks that came with my vest but I only unscrewed them when cleaning them so this really isn't a complaint just an FYI. The pop top enclosures worked great for refueling during my race and gave me zero issues. I opted to go with the 600ml and I'm happy I did as it fits my vest without issue and provides 200ml extra between the two.

I bought this to help identify my electrolyte flask from my water flask during a long run and it's great! You have to press down firmly to make sure the lid is locked on, but once you do it doesn't leak and stays put! It's roughly the same size as the flasks that came with my hydration vest, so I can keep track of my hydration levels easily. When not in use, I can roll it up for easy storage.

I have been using HydraPak bottles for over a decade. The bottles used to be made out of pvc type materials, lids had a gasket that if not mindful of you could loose. After a couple years of regular use the seam would eventually spring a leak and the bottle was done. Honestly they function well and NEVER tasted funky. These new silicone or whatever they are taste beyond horrible, the flip cap is a pain and the way the cap is threaded, the hinge is always pushed into you. The worst is the stupid hinge wears a hole in whatever you’re using it with. I use Bottle Bright cleaning tablets regularly, wash after every use and use filtered water…..this is not a product of operator error. I love the collapsible bottles but will explore different brands.