A outdoor cat
Cats can obviously well against the outside air, they are used to the nature.
But not everyone wants to be outside cats run free.
A cat cage can be very useful.
On that way cats can go inside and outside, both day and night,
When they want to, and all without the dangers of cats that run free.
The extra door works then as lock, so that you are always in control of your cats.
A raised bevel of Plexiglas and aluminum profiles, prevent the cats from the balcony edge off want to jump or run.
This same system I had in my previous House on the balcony, and worked perfectly.