Trying to find water level controller

I know that I have seen an online retailer who sells water level
controlled switches which consist of a tube-like sensor which sits in
the sump which is connected via airline tubing to a switching module
in which you can plug a pump. Does anyone know where to find such
switches. P.S. I know that there are electric level sensors, but I
need the one using airline tubing between the sensor and the switching
module.