Excellent protection against martens, electronically from generated acoustic vibrations. A piezoelectric transducer operates with a frequency of 23 kHz at intervals of 1 s each. Time and 3 seconds. Time exceeded. Martens avoid this frequency range, people and animals are not affected. LED function control. Simple installation, like pre-wheat. Consumption 0.1 watt/hour. (8 mA) - volume/sound pressure of approximately 85 dB, dimensions of 9 x 5 x 3 cm