These are the companies specialising on Invisible Grille. Like many, we do not want to install the conventional grille in our rooms that make us feel like imprisoned, I'm glad that there're others who share the same thinking as us and come up with this idea.

However, I do not suggest Invisible Grille in your bedrooms, you'll know after reading my below comments.

Installing iron grill in standard pattern maintaining the uniform of building, but invisible grill maitaining the natural of building. trust me, just take a look. the 'Insivible grill' is just a name in marketing strategy, it is NOT grill actaully, but just a powerful security string.

the invisible grill aka string 'grill' doesn't affect the VP outlook. you can check first and have a look. the string is neat and almost unseen from far. i doesn't install it because i personally prefer the conventional grille.

My two bedrooms are installed with the conventional grille, sometimes I do hang my children clothes there for drying purpose, but you can't hang anything on the invisible grille, it'll be loosen. The conventional grille looked more durable.

Besides, do note the gaps between the wires are very narrow, thus it'll be hard to open and close your windows, especially if you're short. For me, I'll need to use a clothe hanger to close the windows.