Which main o-ring replacement should I use for a sunlight C4 or C8 light, 19925 or 19922?

Late in the year 2000 UK changed the size of the main sealing o-ring used in the sunlight C4 and C8 lights to one which had a slightly larger cross-sectional diameter. To allow for the slightly fatter o-ring a slight groove was cut into the case at the base of the threads. Lights made after this change use the 19925 o-ring and earlier models use the 199222 o-ring. All Light Cannons use the 19925 o-ring even though there is not a groove in the case. The picture illustrates the differences.

The following flashlights are dicussed:

C4 Xenon,
C8 Xenon,
C4 eLED®,
Sunlight C8 eLED