Some attractions have reflective captioning for people with hearing impairments. What look like small rectangles of black plastic in the picture are screens that reflect text that is actually scrolling along the back wall of the attraction in reverse (mirrored)--the text is part of the attraction itself and is always there, it's just not visible unless you're looking for it.
The device is kept at each attraction that has it and the Cast Members at that attraction will set it up for you. It may be necessary for you to adjust it a bit for your best view.
