After spotting a mouse come out from under my kitchen cabinet one night, I decided to buy this product. I was glad to see that the manufacturers recommend just one unit per floor (I was ready to buy half a dozen!) The day after I installed it, I went to unload the dishwasher just as the red light started blinking (it runs in 90 second cycles) and a mouse sprang off the counter. I've never seen a mouse on my counters, so I thought this behavior was atypical and probably caused by the device. Needless to say, I was freaked out, so that night I performed a test. I placed a walnut on a glue trap underneath the cabinet where I originally saw the mouse. I let it sit there overnight and was afraid of what I might find in the morning. However, I'm happy to report that the walnut was still there (and more importantly, there was nothing stuck on the trap)! I haven't seen any mice since, so I would recommend this device.