Effective gadgets for side visibility?

I asked them they said:

Devices are not lacquered, but they do work in a light rain and they're fully washable with water, brush and soap (of course the battery must be removed)

Bumpy roads can be a problem, but for the 4 months of riding no batteries were lost, no devices were lost or broken :))) The worst thing that can happen - it may turn off (high speed + big bump).

the circuit's exposed so I guess it might not work in heavy rain, but then the water doesn't hurt it either (since you can wash them)