The sensor modules of KMI 15 and KMI 16 series provide a simple and cost effective solution for rotational speed measurement in both automotive and industrial applications. They consist of a magnetoresistive sensor element, a permanent magnet fixed to it and an integrated signal conditioning circuit. Application relevant items such as mounting, electrical properties and possible encapsulation are discussed. Test results of the electromagnetic compatibility are shown and an interface circuit for improved protection of the sensor module is proposed.