Invisible grills is the latest when it comes to bird protection and safety of children at home. Most modern highrises do not allow the installation of metal grills in your windows and balconies as it spoils the facade of the building and gives lots of load. Invisble grill as the name suggest is not only very insconspicuious but is also safe. it is very good looking from inside the house and from the outside. It is rust proof as it is made of SS and has a durable nylon coating.