Get rid of it! As mentioned its not a marine item and theyre really prone to corrosion, particularly at the fuse end because theyre aluminium and the dissimilar metals cause a corrosion cell. a reasonable cheap alternative is the moulded rubber cased blade fuse holders. you can get a 4 inline one, each fuse has a rubber cap and can be rammed full of vaseline.
I had one like yours on the landy and it left me in the dark too many times
i think theyre OK mounted inside a DRY vehicle. no good in a landrover