What do these manual breakers and blade fuse protect??

[OregonPerson]

There are two manual reset breakers (red) mounted to the front of the trailer frame after batteries along with the 30 amp main fuse (green wires) next to battery on my 2018 212QBW with power tongue jack.

What are the purposes of the two manual reset breakers and the main fuse?? I realize they are protecting the wires from over heating and shorts to things, but what are they protecting ie batteries from charger/converter or power center from batteries??

Thank you,

[Greg&Nancy]

One of them probably protects your power tounge jack. I know this from experience. I blew mine by not letting go of the up button on the tounge jack once. I think it is a 30amp fuse. At least that's what mine is on our 2017 28RLS. Hint: keep spares on hand.

[NewBlackDak]

The other is probably reverse polarity fuse.

[MccBob]

I blow the jacket fuse all the time. Can I put a breaker in place of the fuse. I think they make a 30 amp breaker?