BATTERY OPERATED - Operates up to 75 hours on 3 AA batteries (not included). PORTABLE & COMPACT - The portable, compact design makes this sleek Serene Evolution noise machine essential for home or travel. Easily pack it into your luggage or bag for on-the-go convenience, or place it in your bedroom, living room, or office, for calming sounds anywhere in your home. OPTIONAL TIMER - Leave this soothing noise maker on all night or set a timer for 30, 60 or 120 minutes. The Serene Evolution adult noise machine recalls the last sound and volume setting making it the ultimate white noise sound machine for adults, kids, and babies. FALL ASLEEP FASTER - This miracle noise cancelling sound machine masks background noises like barking dogs, snoring, and loud neighbors which helps create the ideal sleep environment. 18 RELAXING SOUNDS - 3 fan sounds, brown noise, pink noise, white noise, ocean sounds, rain sounds, brook, summer night, frogs, bird, hairdryer, crowd, fireplace, 2 flute and wind chimes