REFERENCE 3902 The new Portuguese Yacht Club Chronograph has all the precision of a nautical instrument in its genes. Powered by the rugged IWC-manufactured 89360-calibre movement and water-resistant to 6 bar, the chronograph demonstrates its sporting qualities with a flyback function and an additional flange with quarter-second calibration for recording short periods of time. Longer stop times (hours/minutes) can be read off like a second time on a separate analogue subdial. Ref. IW390210 has a stainless steel case and a black dial.