The Omega Speedmaster Professional ref. 3573.50.00, known as the 'Sapphire Sandwich,' has sapphire crystals on both front and back. It was produced from 2002 to 2015; ref. 3873.50.31 is similar but on an alligator strap.
Movement Type
Manual Chronograph
Caliber
1863Jewels
18
Reserve
48
Frequency
21600
Hands
Small Seconds
Shape
Round
Lug Distance
20.00 mm
Material
Stainless Steel
Glass
Sapphire
Diameter
42.00 mm
Water Resistance
50.00 m
Dial Color
Black
