Very glad I bought this.  My wife has a similar but battery operated book light by the same company, and like that one, this light is quite well built.  It plugs into a USB port and has 2 brightness settings and an off setting.  The highest setting is indeed "Mighty Bright!" The lower setting is the one I personally prefer when working in the evenings. But it's nice to have both settings and either one will illuminate the full keyboard nicely.