[–] [Deleted] 5 points (+5|-0) Edited

These look like 4mm G4 bi-pin lamps. Mostly used in panel boards for indicators. Normally with halide or xenon and they have thick elements so they last a long time. We're talking years. You don't want your nuclear reactor or missile launcher bulbs burning out.

[–] Polsaker 3 points (+3|-0)

It might be a lightbulb but the filament inside looks too thick, maybe it's some kind of sensor

[–] pembo210 2 points (+2|-0)

yeah, I'm thinking little lightbulbs as well. Maybe a small flashlight or christmas tree lights replacements.

This is the bulb in my Surefire flashlight. The bulb itself is about as big around as the nub on the top of a AA battery

[–] PhunkyPlatypus 2 points (+2|-0)

Perhaps lights for some sort of circuit board?

Judging by the gauge of the metal compared to the size, I would assume they're for something heavy duty or long lasting. The (what i assume is insulation) makes me think they may be heated to high temps.