The repellent works well, tested with my dog, it does not support the location where the appliance is installed, cats are not approaching, the only downside is the scope of ultrasound about 6 m to book only because the passages with a large garden, it would take at least 25 aircraft to have an effective safeguard day and night throughout the garden, hello batteries !!! repellents are also available in solar but I do not know if it is as good, is self sufficient after several days of rain ??