Combo T-20 Reflex Right Angle Mirror Viewer Magnifier: In excellent shape, very clean. The glass and mirror are free of any scratches, haze, fog, or fungus. The rubber eyepiece is soft and supple. This T-20 model rotates for landscape and portrait view. I was told that this viewer is compatible with the Calumet, Canham, and Walker 4 x 5 view cameras, but I can't guarantee it. This view camera accessory provides a right side up image for easy focusing and composition, with a built in magnifier. Clients and art directors like it alot, as they don't have to stand on their heads to see the image.