Nice concept with a novel lens design. It is flush mountable but the wire protrudes from the small end begging the question, what do you do with the wire? I dismantled mine and brought the wire out through the center of the backing plate. A small hole in your mounting surface hides the wires completely giving the marker a factory appearance.
The three main parts, the body, lens and backing plate are plastic and sealed with silicone. The silicone application was inconsistent and would have allowed leaks.