MSR has made a great hydration bag that is tough, durable, and well designed. The large opening allows for easy filling and the cap and nipple dispenser seem to be durable (no leaks so far). I also like the grommet and lashing cord system that allows me to tie this bag to the outside of my pack when carrying a lot of gear. At 6 liters its a big bag but it fits easiy into the hydration sleeve of my Kelty Redwing 3100. If I dont want to carry so much water I simply add what I need and roll up the unused part of the bag to save space. One nit pick: the cap and tube connector protrude at least 2 inches from the bags surface and interfere somewhat with loading other things in my pack. Overall I rate this product highly and recommend it to anyone who needs a large volume hydration bag.