Additional Information: Brand new Harry Winston Project Z5 Zalium World Time Tourbillon gent’s watch, Model # 400-MATTZ45ZC-A. Limited Edition only 150 pieces made. Zalium 45mm round case. Bluish grey dial with dual time sub-dials, world city display and open tourbillon displays. Hours, minutes and seconds. Swiss automatic movement. Sapphire crystal front and back. Rubber strap with zalium pin buckle. Water resistant up to 100 meters. Zalium - used exclusively in the aerospace industry and patented by Ronald Winston himself.Retrograde - a watch with a retrograde display does not display the function in a circular fashion, as we are used to seeing. Rather, it sets out the functions in a linear manner. Instead of the hands going round in a circle, they travel along an arc, and when they get to the end, they jump back to the beginning.Tourbillon - compensates for differences in rate caused by a watch adopting different positions. The principle is to mount the balance and escapement in a rotating cage. The balance and escapement rotate around their common axis going through all positions to average out the errors. Tourbillon cages or platforms usually rotate once per minute but 4 minute and six minute tourbillons are also found. The Tourbillon complication is an extremely difficult accomplishment to achieve and generally demands a high premium. Subject To Availability