Caroline was in a large orthopedic bed with an overhead frame.

Cole opened the door that connected the cells to the main office, ducked under the overhead frame, and started down the long, narrow corridor.

Grips use overhead frames up to 20'x20' or larger for the shaping or filtering of sunlight.

From its shape, it was probably another lens that served as part of the oversize microscope; The overhead frame was wedged more tightly than the lower one.