Rubber washers under the control dials keeps the unit in fine tune. It is very easy to slightly knock out of tune while in use. I put mine inside a waterproof box. To avoid dirt and dust. Avoid knocking out of tune and also protection of the not so strong plug connector.
I used a waterproof cable housing for passing through the deck of boats to exit the box.
I didnt try and go under water with it but But I can certainly use it in heavy rain not that I do..