Those are resettable fuses. They're kinda like circuit breakers. If they're manually resettable they'll have a small button on one end.
The picture doesn't show where the wires go, but the end with the metal bar jumper should be the battery end (most likely the big red cable) and the other ends go to other equipment (converter, jacks, etc.).
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Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!
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