Great size and quality.
I have the 5, 4, 3 and 2.5L bladder and this one is a nice fit on the standalone cooling backpack.
The autonomy is also enough for me. The Weight to cooling duration ratio is nice with the standalone backpack. I really use the cooling feature of the standalone backpack on my way back in the evening when i'm inside the train to keep me cool during hot summer day.
I had an issue with the dual chamber, 4 litter bladder. The closing cap had an issue i believe and the water from the middle pouch was leaking. With this one i have no leaks.
