I was not sure if the device is not working? Yet there the tester !!!! but when I go into the kitchen at night the cockroach has its side of the device !!! and he has even engulfed the hole below when I take !!!! Anti harmful NO !!!! consumes power for nothing YES! PS. I have a neighbor who has a buy but not on the seller and that works very well, and that makes one month that I plug it!