Features: Our water filter coupling have inner diameter of 28mm on both end, suitable for 28mm external thread water filters and standard plastic water bottles. Suitable for directly drinking water, backwashing or setting up a filtration system when hiking or camping. Use our filter coupling to connect the water filter to a cleaning water bottle, and can quickly backwash filter. You can also use it with a thread water bag to build a filtration system, so you can easily get a lot of cleaning water and release your hands. Our 2pcs water filter adapter is equipped with 10 replacement spare gaskets, which fit tightly with the couplers, effectively improving the sealing performances, preventing water leakage and improving water filter efficiency. Specifications: Component: Silicone Size: about 6.35x5cm/2.5x1.97inch Package Includes: 2Pcs Filtration Cleaning Couplings 10Pcs Filter note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.