Hydrostatic Backerplate provides structure to reservoir allowing it to easily be shoved into a loaded pack and provides a flat profile Easy slide top opening seals watertight and provides wide access for filling and cleaning Pour Shield extends the collar to ease filling in shallow sinks Carry handle Magnetic bit valve Hydrapak blaster bit valve offers fast, smooth water flow with 1/4 twist on/off Quick connect system allows for easy removal of reservoir Ergonomic handle allows for true on-handed filling, making it easier to carry and pour as well Compact bite valve provides excellent water flow Thumb-operated on/off lever is easier than ever to operate with one hand Compact Slide-Seal opening aids one-handed filling, removes bulkiness, slides into packs easier and seals securely Seamlessly integrates with new HydraClip reservoir hanger in packs for secure carry Exceptionally secure hose magnet system Center baffle and backer plate flattens the profile while carrying stiffness through to the front panel, reducing bending and buckling while loading

In heavy rain, you are going to get some leakage at the shoulders unless your pack is really full and pushed up high
While I did not get to test this bag in a downpour, it seems to be capable in light to moderate rain, without the need for a roll-top or some other trickery
Features: Fjllrven bags come with various features, such as laptop compartments, padded straps, and water bottle pockets
If your child has a shallower head, these helmets may be too deep for them and come down too far over their eyebrows