O-ring size for Foursevens Mini ML 123?

[pendragon1998]

Last time I replaced the battery, I somehow lost the O-ring that goes around the base of the threaded end of my Foursevens Mini ML light. The best I can measure using digital calipers, it looks like the slot is 17 or 17.5mm diameter, but I was wondering if someone could point me towards the correct size o-ring to replace it?

 

[DaveTheDude]

Mine measures 17.6 mm (digital caliper). That noted, my Mini ML 123 is 10+ years old, so the O-ring may have stretched just the teeniest bit since it was first installed.

Considering however that O-rings are dirt cheap. just get a kit containing various diameters and thicknesses and mess around with it until you find the correct one.