This version has a lightweight but strong back that helps prevent bending and breaking during filling, making it ideal for both internal and external backpack pockets specifically designed to store a hydro bag. BPA free. The ergonomic handle allows one-handed filling and makes carrying and pouring easier. The compact mouthpiece ensures perfect water flow. The thumb-operated on/off lever on the mouthpiece is now easier to operate with one hand than ever before. The compact Slide-Seal opening facilitates one-handed filling, reduces unnecessary volume, slides onto the hydrobag more easily and seals perfectly. Seamless compatibility with the new HydraClip hydrobag hinge (for safe carrying in backpacks). Hose with extremely safe magnetic system. The center bulkhead and rear gusset flatten the profile while reinforcing the front panel, reducing flexing and buckling of the hydrobag when stowed in a backpack.