Can be used for vehicles and road.
They are always made of glass. Thus they can be easily damaged, therefor they are available with a plastic sheath.
They are manufactured as a single switch (normally open) or as changeover switches.
In order to build a normally closed switch, a small magnet comes to the reed switch.
So it is turned on in resting possition. A counter magnetic field cancels the function.
Therefore, it may malfunction when it comes close to motors.
Readjust the magnets can eliminate the problem.