Platypus reservoirs have always been considered the best in the industry because of their taste free inner layer and their durable outer layer. The Big-Zip LP (Low Profile) adds a web to keep the reservoir from ballooning. The improved shape is more comfortable on the user's back and easier to slide into a pack.
The layered film used to achieve the taste-free and toughness properties is complex and expensive to manufacture. The reservoirs were already one of the highest priced and Platypus could not afford to raise prices with a feature that many companies were already selling.
The updated product simply adds a web of taste-free material to the inside of an existing reservoir. Special attention had to be paid to so that features such as cleanability, durability and taste-free were not lost during the revision.