Nautilus 40mm Stainless Steel w/ Leather Strap 5726 40mm stainless steel case, sapphire crystal back, screw-down crown, black dial with gold applied hour markers with luminescent coating, self-winding caliber 324 S QA LU 24 H movement with day/date/month annual calendar with moon phase and a.m./p.m. indication, approximately45 hour of power reserve, leather strap with fold-over buckle. water-resistant up to 120 meters.