4 x o-rings to fit the following Suunto dive computers:

X6HR
Observer
G6 Pro
M3
X6
S6
G3
T6

The high Scuba grade specs are:  

Manufactured from Nitrile 70° Shore HardnessManufactured to the following international standards: ASTM D2000 DIN3770 M2BG714 A14 B14 EA14 EO14 EO34 EF11 EF21 F17RoHS Directive 2002/95/EC compliantColour: BlackOperating temperature range: -30°C to +120°CNitrile N70 is also known as Buna-N Suitable for static & dynamic applications.  

Great as a spare.
THESE ARE MADE ESPECIALLY FOR THIS APPLICATION NOT OFF THE SHELF SOMEWHERE NEAR WATCH SEALS.