Ultrasonic sensors are used wherever optical sensors are not considered appropriate (e.g. for products with variable light transparency). Our ultrasonic sensors scan the web edge with a pulsed ultrasonic beam. This avoids "standing waves". The receiver establishes an analog voltage signal that is proportional to the impulse intensity. When the web reaches the air gap, the impulses are weakened. This enables the sensor to precisely recognize the web edge. Among other things, our ultrasonic sensors are used for scanning of materials that are opaque to sound, such as paper, plastic and metal films. The wide range of construction sizes from the compact FX 46 to the FX 5200 with a fork width of 124 mm leaves nothing to be desired and enable reliable and certain identification of deviations.