We designed our outdoor repeller to cope with northern European weather, unlike many other "fair weather" products. This highly featured repeller has three frequency settings, so you can target the sound to the type of pest you want to repel. The ultrasound noise can be heard by the animal up to 75 feet away, but it is outside the normal human hearing range, so it doesn't bother us. (some children with excellent hearing may be able to detect the lowest frequency sound, which we use to repel large animals, but is is highly unusual for anyone to hear the at the cat / rat / fox / rabbit or squirell frequencies). To operate, first decide on whether you want to use battery or plug-in power (adapter required, supplied separately). Then mount on a wall, fence or rod, using one of the three mounting accessories provided, and point at the problem area. You have a choice of activating the sound whenever motion is detected by the built-in infra red sensor, or activating continually. Most pests quickly learn to associate being in your garden with the unpleasant noise, so they just decide to stay away. Some animals learn this behaviour virtually overnight, but in most cases it takes a little while for the message to sink in. We have lots of testimonials from people who have used this product to sort out problems with cats, badgers, and foxes. We are really proud of the fact that our product is the top selling outdoor pest repeller in the UK.