The PC6089 has a unique side panel that can be with or without a window.
As standard, an aluminum panel sits on the inside of the acrylic window and is retained by screws and four metal plates.
Remove the screws and the panel comes out revealing the window and its also unique "Tridimensional Graphic" as Lian Li describes it. According to Lian Li themselves, the metal insert is fitted to comply with EMI shielding regulations.
The other side window is standard as they come. As usual, the side panels (and everything else actually) are retained by thumbscrews.