Perfect Compatibility: Our water filter coupling has an inner diameter of 28mm on both ends, which is compatible with 28mm external thread water filters and standard plastic water bottles, suitable for direct drinking water, backwashing or setting up a gravity filtration system when hiking or camping. Strong Sealing: Our 4 pcs water filter adapters are equipped with 20 replacement spare gaskets, which fit tightly with the couplers, effectively improving the sealing performance, preventing water leakage and improving water filtration efficiency; Sufficient quantity to meet the spare needs of outdoor activities, and can cope with the situation of loss or wear and tear Wide Application: Use our filter coupling to connect the water filter to a clean water bottle, and you can quickly backwash the filter element without carrying a bulky syringe; You can also use it with a threaded water bag to build a gravity filtration system, so you can easily get a lot of clean water and release your hands Lightweight and Portable: Compared with bulky syringes, our lightweight water filter connector is more suitable for long distance hiking, camping and emergencies; Small and light and does not take up space, you can carry it with you without burden, making your outdoor equipment more streamlined Easy to Use: You only need to connect the water filtration connector with gasket to the outlet end of the filter first, and screw the other end of the connector onto a plastic water bottle (28mm thread) filled with clean water, and then push the bottle hard and continuously to backwash the filter until the water flows clear, and you can get a clean water filter Color: As Shown Material: plastic Package Contents: 4 pcs x water filter adapters 20 x replacement spare gaskets