45.5 mm, black ceramic on leather strap with rubber lining^OMEGA Best

Anti-magnetic

The movement is unaffected by exposure to strong magnetic fields, even those greater than 1.5 tesla (15,000 gauss).

Chronometer

Label given to a watch which has undergone precision tests and received a certificate from an official body (COSC).

Date

The day of the month, displayed in a window on a watch dial at the 3 or 6 o’clock position, or within a subdial at 9 o’clock.

GMT

A watch with a 24-hour index and an additional hour hand which indicates a second time zone and completes one full rotation in 24 hours.

Helium escape valve

Decompression system which allows helium to escape from inside the watch when the watch is worn for professional use in pressure chambers. (Long-term underwater work, crude oil exploration, etc.)

Master Chronometer Certified

Guaranteeing the Swiss industry’s highest standard of precision, performance and magnetic-resistance, as set by the Swiss Federal Institute of Metrology (METAS).

Screw-in crown

Self-locking crown, screwed into the tube of the case, used for highly water resistant divers’ watches.

Time zone function

Allows the hour hand to be easily adjusted to different time zones without stopping the watch.

Transparent caseback

A transparent caseback – frequently made of sapphire – makes it possible to see the movement inside the watch.

Unidirectional rotating bezel

A bezel which turns in only one direction. Particularly useful for divers who cannot accidentally rotate it in the wrong direction, which could cause them to miscalculate their dive times. A rotating bezel makes it easy to measure elapsed time.