Review on Maximize Hydration with our Hydration Bladder - 3L/100oz & 2L/70oz Options! by David Stewart

This is the second bladder I've bought and it works great but I'm not sure if it's a design change or a different pad that does closing this bubble makes it difficult to save constriction. It might just take a bit of work, but I usually have to open, close and check the seal on the main port at least 2-3 times before I can get a seal that doesn't leak. Otherwise it works great and is exactly what you would expect from any of these things.