Iwc, Portuguese series, model: IW371610 Grey dial, complete set, automatic winding, 18K red gold, case diameter: 41.0MM Model: IW371482, diameter 40.9mm, 18K rose gold all-gold case, thickness 12.3mm • Strap: Original black alligator leather strap, folding gold clasp, classic configuration for formal wear • Dial: Rock grey brushed dial, blue ring track chronograph scale, willow-leaf hands + Arabic numeral hour markers; Double small window timing layout 6 o 'clock small dial: 30-minute cumulative timing ◦ 12 o 'clock small dial: 12-hour cumulative timing • Waterproof: 30-meter daily water resistance Movement configuration Equipped with the Cal.79350 automatic chronograph movement (based on the improved 7750), it features 25-jewel bearings, a frequency of 28,800 VPH, a 44-hour power reserve, a tight caseback design, and Geneva stripes on the plates. Design highlights Classic Portuguese thin dress: Inspired by the design of Marine pocket watches, with an ultra-thin case, it is IWC's most classic dress chronograph wristwatch. The grey plate with gold edge color scheme: Grey plate + rose gold shell + blue border scale, retro and stable, the preferred color for business formal wear. Double-button chronograph: There are two gold buttons on the right side, upper and lower, and the middle crown is used for time adjustment.