The NSN (National Stock Number) 0555/6645-99
decodes as follows:

0555 "Royal Marines"
6645 "Time Measuring Instrument"
-99 "United Kingdom"
116/97 is the issue/serial number of this watch.
CWC (Cabot Watch Co.)
Royal Marines Issue

Case Diameter: 42 mm
Case Height: 12 mm
Case length: 47 mm
Lug Width: 20 mm
Movement: 7 jewel ETA
955.122 quartz, hacking
Case material: Stainless steel
Crown: Screw down
Bezel: Uni-directional, indexed
w/ 60 clicks
Water resistance: 300 meters
Vintage: 1997

Cabot Watch Company has
been manufacturing watches for
the British Military since 1972,
and is today their major supplier
of watches. This watch is the
current British Royal Navy issue.

Additional pictures