This UR-100 is made of one of the oldest precious metals: Electrum. Electrum is a natural occurring alloy of gold and silver, with copper and other metals. In ancient civilizations, electrum was used to produce coins for currency. While displaying hours and minutes like previous UR-100 models, the Electrum also indicates the distance travelled by the Earth at the Equator. Limited to 25 pieces. Brand: Urwerk