This Serene Evolution 36 sound portable white noise machine is absolutely wonderful. It has 36 different noises to choose from to enable you to have a good night sleep or just listen to and be calm while you're doing work. My favorite sounds are the ocean, waterfall, the crickets, the birds and the wind chimes. I love how this machine is so small and compact and very easy to take along with you when you travel. You can leave it on all night or set the timer for 30, 60 or 120 minutes. It comes with a rechargeable battery and a USB cord. I really have enjoyed using this sound machine.