Fill your hydration pack reservoir directly from your screw on/off filter without removing it from your backpack with the Sawyer Fast Fill Adapter (hydration pack and filter sold separately). This handy Sawyer "hack" makes refilling hassle free. Adapters attach directly to the drinking tube on most hydration reservoirs. Designed for use with industry standard 1/4-inch inner diameter tubing, it's compatible with the Sawyer Squeeze Filters and Sawyer MINI Filters. Sawyer Products has offered the best, most technologically advanced solutions for protection against sun, bugs, water, and injuries – everything from first aid kits developed for wilderness to point-of-use water filters that filter contaminated water to levels cleaner than U. S. bottled water.