This unique clock is covered with more than 98 million pieces of colored glass mosaics in addition to more than two million LED cells for illumination. In addition, the clock is covered with more than 43,000 square meters of advanced carbon fibers. Each hand of the clock is powered by an independent motor, both of which are contained in a single assemblage which weighs more than 21 tons, thereby making it the biggest and heaviest clock operating assemblage anywhere. The clock is powered by four operating units, one for each of its faces, and each face receives the same signal at the same time, in coordination with the most modern atomic system in the world. The crescent which crowns the tower is also considered to be the largest in the world, with a diameter of 23 meters. The length of the Arabic letter 'alif' in the phrase "Allah Akbar" (God is great) is more than 23 meters. The call to prayer resounds from the pinnacle of the Makkah al-Mukarramah Clock through the most powerful sound system of its kind, and during the call to prayer 21,000 green and white lights illuminate the clock, thereby increasing its visibility in all areas of Makkah al-Mukarramah. --SPA 14:36 LOCAL TIME 11:36 GMT www.spa.gov.sa/w