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 Model: UR-100 Electrum Reference Number: UR-100 Movement: Automatic Case Material: Electrum Yellow Gold Case Size: 41mm Dial: Black Bracelet/Strap: Leather Gender: Men's Watch/Unisex Warranty: Manufacturer's 2 Year Warranty Features: Satellite Hours and Minutes Rotational Distance at Equator Orbital Distance Shop other beautiful pieces in our Urwerk Collection. For inquiries on the piece please contact: boutique@shsilver.com.