I initially bought me this year, the first of these devices after the cats have always left their mark in the garden of the area at night. For 3 weeks so far everything clean. The second unit I bought for the carport for the Mader - here I can not say much about it - until now, however, no traces. The third device I have now used for our new façade - the thermal protection with the gleaming white façade should apparently attract the birds that make it on the windowsill comfortably and then contaminate the facade with their droppings - that is rid of any more. I have now put such a device on the window sill in 2 meters height and the last few days I had no impurities. Pay now even order me a 4th device. This gabs überigens even at Hofer (Aldi) in Austria, however, more expensive to 1/4.