Trixie Protective Grille for Windows (Side Piece)

I find it to be pretty cheap plastic. Installing it with screws (instead of glue) is really a hassle. And the cats could easily squeeze through, since it bends away so easily, especially the top part. I have a metal one on another window and I'm much more convinced by that. I'll probably take this one down again and put something else up, because I don't want the cats to get hurt.

No proper instructions, and the blocks for fixing are too thick for our window frames.

Unfortunately, it requires drilling, and it's not as universal as the manufacturer claims – it doesn't fit all types of windows. No instructions in Polish.