The Butterfly Waterfall screensaver by NatureScreenSaver.com features an animated waterfall and butterflies in a tranquil spring-time setting. So relaxing, set back and enjoy the sounds of song birds, frogs and the waterfall while windchimes play gently in the distance. Registered users will receive an activation number that fullly enables the screensaver. Entering this number will activate an additional five types of butterflies and the ability to mute the sounds through settings.