The Adjustable H3 SUP Pump Adapter is compatible with a variety of stand up paddleboards and flysurfer. There are three colored rings on the adapter that allow it to fit a variety of H3 valve depths. The black ring is rubbery and provides a good pressure/friction fit while the yellow and green rings are made from plastic and can be taken off to custom-set the depth of the valve. Inside the middle of the adapter there is also a screw that has and adjustable height.