Sound Oasis Sound Cards offer unlimited sound environment possibilities with the world's first and only memory cards that allow sound machine owners to expand their collection of sounds. Sound Oasis Sound Cards contain our next generation playback technology for the clearest, most realistic sound quality available. For use only with Sound Oasis Sleep Sound Therapy System S-550-05. Sounds included: Thunderstorm in the Wilderness, Loons on Wilderness Lake, Mountain Valley Windstorm, Forest Rain, Waterfall and Roaring Bonfire. .