This is a very easy to fit and use external hard drive. It takes only minutes to set up. It is compact and very quite. The unit does not have an on/off switch but that is not required. The unit fires up when you switch your computer on and then goes to sleep when the computer is turned off. It comes with mains power adaptor and a USB lead. When the unit is set up, it gives you the option as to which files you want to back up from your hard drive on your computer. You also have the option to set a time of day to back up your files if required. It is fast and i am very pleased with my purchase.