Read more Ideal as an alarm for those who need quickly help, like the elderly, child, handicapped, pregnant women or the sick.The nanny of caregiver can not always stay with patients or the disabled, just simply press the call button to get timely and considerate care without yelling.It can also be used as doorbell.Up to 80 meters range in open area (walls and other objects will reduce the range).Using 16-bit encoding to eliminate interference from other devices.No power switch is designed to avoid forgetting.Transmitter is designed with Lanyard, and can hang on neck or put into pocket. Pregnant Women Easily call for quick help with wireless pager set.No need yelling, thoughtful care for the pregnant women.Great and pratical gift. The Aged or Patient or The Disabled 4 level adjustable sound volume, max 110db great for the aged.