It is an engineering wonder designed to dampen the vibrations of the 1,667-foot-tall structure. The 18-foot-diameter, 660-metric-ton steel sphere is hung by eight cables in the tower's top levels and can be seen from the 88th to 92nd floors. The purpose is to reduce noise pollution and improve the viewing experience for people living or working near the site. There are other towers in the world that use a spheroid as a vibration damper. The Shanghai World Financial Center uses one made of glass, while the Petronas Towers in Kuala Lumpur, Malaysia, use ones made of resin. The Taipei 101 Tower's sphere was manufactured by GGG State-owned Steel Manufacturing Corporation in Jiangsu Province, China. It was delivered to Taiwan in 2004 and hoisted into place later that year. The sphere weighs about half as much as the tower it is attached to and contains 2.5 million cubic feet of air. People who work on the 97th floor restaurant of the Taipei 101 Tower can see the sphere hanging in the distance. They say it looks like a giant ball of smoke when the wind is not blowing in the right direction. However, when the wind is howling, it looks like a huge wave crashing toward them.