had it about 3 or 4 years now and its very effective, i bought it because of a bad ant problem,we have nest that seems to be either in wall cavity or under step right outside back door, for many years i had spent the entire summer having to put ant killer down permenantly, bought the machine,plugged it in and within 3 or 4 days not an ant in sight indoors, the nest is still there and the ants are all over the outside wall all summer, but even with he door open they dont come in ( maybe 2 or 3 a year venture in but they are really slowed down and dissorientated and going round in circles lol ) and the added bonus is have not seen a spider indoors since bought it either,i did go for quite a good one about �40 i would really recommed one for anyone that hates creepy crawleys its money well spent :-)