Producing aggressive ultrasonic sounds not audible to humans are found by martens extremely annoying. To be mounted in the engine compartment of motor vehicles. Ultrasonic marten repellent for use in cars, houses and Flats. Produces enormously loud and pulsating ultrasonic sounds. Angle of radiation with a special spherical surface tweeter with about 140 degrees, max. approx. 100 dB +/- 20 %.