Great for backpacking treks or long hikes, the Sawyer Hydration Pack Fast Fill Adapters allow you to fill your hydration pack reservoir directly from your Sawyer screw on/off water filter without removing it from your backpack. The adapters attach directly to the 1/4-inch drinking tube on most hydration reservoirs.FeaturesCompatible with the Sawyer Mini Filters and Sawyer Squeeze FiltersAttach directly to your drinking tube on most hydration reservoirsBest for backpacking and long hikes