As the liquid level rises in the tank, the float is lifted up due to buoyancy. The float moves inside a SS float chamber. External to this float chamber is a glass tube indicating PVC magnetic ball assembly which carries the magnetic follower. Due to magnetic attraction, the magnet on the float and the magnetic follower are coupled and move in union. So as the float moves along with the liquid, the follower capsule also moves inside the glass tube and PVC magnetic ball changes its colour, and the position of the follower capsule/magnetic ball can be read against the scale.