One of the most important IWC of the last 50 years, imo -- and just 12 months away from its 50th Anniversary:

• avant-garde 1970s hexagonal design, eventually by Gerald Genta as many others of the IWC SL series;
• IWCs 2nd DaVinci model with substantial parts of the genetic code of the initial model: Beta21 and a cal2405 stepper-motor quartz-movement ticking at 32kHz;
• 1974 -- 2y after the standard-definition of the AP Royal Oak and 2y before the successful IWC Jumbo Ingenieur was launched with the exact same bracelet;
• IWCs 1st luxury steel-sportswatch and a lavish anthrazite dial that jeweled many of IWCs later 70s and 80s pieces;

The importance is further underlined by the beautiful preserved double-signature on the dial: Chronometrie Beyer, Zurich.