3D Realistic Hourglass Screensaver - Version 1.75 Use this realistic hourglass as your screensaver, add classic style to your desktop.It consists of two glass bulbs placed one above the other which are connected by a narrow tube. One of the bulbs is filled with fine sand which flows through the narrow tube into the bottom bulb . Once all the sand has run to the bottom bulb, the device is inverted in order to measure another time period.it's really an ideal screensaver.