Omega Men's 3557.50.00 Speedmaster Broad Arrow Olympic Edition Automatic Chronograph Watch

This Olympic Edition of the Omega Speedmaster Broad Arrow automatic chronograph men's watch will help you keep track of your road training thanks to its tachymeter bezel. The black dial face includes three tonal chrono subdials as well as a full Arabic numeral readout in a fanciful font. The dial also includes luminous hands (with red seconds hand) and small minute indexes. It's matched to a triple-link stainless steel bracelet that mixes brushed and polished finishes. Other features include a 55-hour power reserve, a scratch-resistant and glare-proofed domed sapphire crystal, and water resistance to 100 meters (330 feet)--offering protection from accidental splashes as well suitable for swimming, snorkeling, and light recreational diving.

This watch also features the Omega 3303 caliber automatic movement, which has been certified as a chronometer by the COSC (Swiss Official Chronometer Control). Only 3 percent of watches produced in Switzerland are "chronometer-certified." To achieve this highly coveted certification, the movements are subjected to numerous tests over a period of 15 consecutive days and nights, in five positions and at three different temperatures.

How to Use a Tachymeter
A tachymeter is an instrument for measuring speed. It is a chronograph with a graduated dial on which speed can be read off in kilometers per hour based on 1000 meters distance. For example, the chronograph indicates that the distance of one kilometer has been covered in 30 seconds. The corresponding point on the tachymeter scale indicates 120, and thus the speed is 120km per hour.