Sorry to hijack the thread (although for what it's worth my fridge is also an N97, so partly relevant)...
Inspired by this thread I've been thinking about winter covers for my fridge vents - I managed without them a couple of weeks ago when the temperatures outside were only just above freezing, but we plan to do more winter caravanning so perhaps I should consider them.
The vent covers I've seen online are all sold in singles - do you only use one, or do you need two and cover both vents?
Given they're thirty quid each, like Chris I am considering something home made with perspex and magnets!
UPDATE - if it helps anyone,
https://www.perspexsheet.uk/4mm-clear-000-perspex/ will currently supply two pieces 4mm thick, in the sizes Chris specified, for about £20 inc postage.