This is a Float switch or Fluid level controller with 2 meter Cable used as a sensor for Water Level Controller.
Advantages of Float Switch :-
Sturdy and durable & need no maintenance.
No current / voltage is passed through water, therefore no electrolysis or Salt deposition.
Long life (approximate 10 million operations)
Rust proof (entire sensor body in polypropelene)
Can be used in hard water or fuel such as diesel, kerosene, oil etc. (not recommended though).