This gauge will fit most of the BOSTON type valves in float tubes, belly-boats, and may pontoon-type water crafts.
This gauge comes with a ring-style adaptor that may be needed on some versions of vales. Slide the ring adaptor onto the gauge tube body with the thickest portion of the ring facing upward. Make sure the ring is snug.
Insert the pronged end of the gauge into the valve firmly to get the pressure reading.