Steel on steel
Note: watch no longer available
The day of the month, displayed in a window on a watch dial typically at the 3 o'clock or 6 o'clock position.
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.)
Self-locking crown, screwed into the tube of the case, used for highly water resistant divers' watches.
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.
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