When I bought my Osprey backpack, I also purchased a Platypus 2 liter Big Zip LP Reservoir to go in the pack. There was an assortment to choose from. I chose the Platypus reservoir based on its features over the other reservoirs. Platypus Reservoir Features Wide-mouth opening makes filling, emptying, and cleaning the reservoir virtually effortless. It lays flat when filled so it works well in the pack. The lid has a durable flap that you use to attach the reservoir in the backpack. … [Read more...]