Plastoferrite is used in the classical case in which the signal has to be maintained for an elevated length (for instancs for presence floor signaling).
If instead signals must be supplied in specific points of the rail (for instance for acceleration or deceleration in proximity of the floors) magnets of different materials (ferrite, neodym) can be used both for monostable and for bistable sensors. They have higher magnetic flows and therefore if they have the same dimensions, activation distances can be higher or viceversa, with the same distances, we can use smaller dimensions.