Masks Noise - cancel out noises that might disturb or distract, for improved sleep and concentration.3 Sound Options - Bright white noise, deep white noise and gentle surf.Portable - Perfect for travel and on-the-go use (includes clip for easy handling or hanging).Rechargeable - Convenient USB charging (USB cable included).Guarantee - Backed by a one-year limited factory warranty and the always exceptional Yogasleep customer service promise.Please note: This sound machine is intended for portable use. For optimal performance, do not leave continuously plugged in for longer than 14 days.