I bought this, because we'd started having a real mouse problem in our home. I plugged it in, and I waited for the recommended 6 to 9 days. After 3 weeks, we set mouse traps in front of it and were catching mice daily. This didn't deter them at all.I actually came into the kitchen one evening to turn off a light that had been left on and saw a mouse sitting in front of the unit eating some crumb my daughter had dropped.The unit may have been defective (no way of checking), but I wouldn't have another one.