What do you get when you blow into one tube with two diameters? The Venturi effect, of course! A Venturi tube is a tube or pipe that has two different diameters. When fluid or gas flows through the more narrow section of the tube, pressure is reduced and flow velocity increases simultaneously. This phenomenon is the Venturi effect. Venturi tubes are used in meteorology to measure pressure differential and also used in aircraft systems to measure air and fuel flow. The U-shaped tube in this apparatus can be filled with a colored liquid. Then, air is blown into the system to demonstrate how the pressure changes. Includes a glass Venturi tube, U-shaped tube, two rubber hoses, clamps, and is mounted on a sturdy support. 17½" x 5" x 12½".