Very often with taller cages there is the worry of your pets falling from the top to the bottom.
By having a central mesh level with corner cut out for access, not only prevents this but another advantage is that it doubles the floor area of a cage
Really tall cages can have more than one mesh level
The price of a level includes any extra dooring required either for your access or side doors if required for shelf changing.
PLEASE BE AWARE THAT MESH LEVELS ARE FITTED WHEN BUILDING A CAGE,THEY ARE NOT ALWAYS PRACTICAL TO FIT INTO AN EXISTING CAGE.