Omega Men's 3573.50.00 Speedmaster Professional Mechanical Chronograph Watch Importado Omega 1863 Caliber Swiss mechanical-hand-wind chronograph used on the Moon; 48-Hour Power Reserve Scratch-resistant sapphire crystal with anti-reflective treatment on both sides Case diameter: 42 mm Stainless-steel case; Black dial; Chronograph functions; Tachymeter function Water resistance : 5 bar (50 metres / 167 feet)