Multi-sound options plus timer: Choose from six sound options and then set the sleep timer to 45m, 90m, or 8 hours Six soothing sound options: Sound settings include white noise, brown noise, rain, ocean waves, and a calming lullaby. 25 adjustable volume levels. Unbeatable quality & guarantee: For over 50 years, Yogasleep has been the gold standard for white noise machines. Backed by a one-year limited warranty and exceptional Yogasleep customer experience, we stand behind each product and offer you a 30-day return policy. Simple to use: No battery required, powered by USB cord, and features simple, intuitive design and buttons. USB power adapter wall plug not included.