Underwater contour display: The portable fish finder has 3 colors display modes to show underwater contour display, blue, red and gray. It is clear and professional. Sensitivity Adjustment : It controls how many details are shown on the display. You can set up the sensitivity from 1 to 10. We recommend you to choose lower sensitivity if fishing in clear water. Fish alarm : The kayak fish finders alerts you when it detects fish or fish schools by alarm setting. It can distinguish the relative fish size and shows in large, middle and small icon on the screen. Measurement Unit : You can choose four different units from the menu--M/℃, FT/℃, M/℉, FT/℉. Multi –ways to use Lucky portable fish finder Attach the adapter to the fishing boat hull by the mounting tabs. Fix the transducer against the hull bottom 1 inch underwater. Make sure the moving speed is lower than 5mph. Cast the sonar transducer as far as you can, and use the fish finder portable in ice fishing, river fishing, sea fishing, kayak fishing, shore fishing and so on.