Excellent product, simple yet super effective, and I highly recommend it. We've had this for around two weeks now, and it's been excellent at repelling cockroaches from our apartment. We had been seeing roaches for over a year, and our superintendent brought in exterminators to gas our apartment two times and do other treatments, and they would disappear for a while, but always start coming back. A few weeks ago, we were seeing at least two roaches every day, and we decided to try out this ultrasonic repeller. The package comes with 6 units included, so we set up 2 of them in the kitchen, 2 in the dining room, and 1 in the bathroom (where we were seeing the roaches the most). I was doubtful at first, but once we set them up, I saw only 1 tiny cockroach in the kitchen the day after, and didn't see a single other cockroach since then! Last week we reduced the number of units being used (we're not sure what sort of impact it is having on us, even if we don't hear it), and we are constantly on the lookout for roaches, but still haven't seen any. This is now a must-have device for us wherever we may be. We're excited to take it with us on our travels and see how it works on mosquitos and other bugs.