Umbra Conceal Double Wall Book Shelf, Nickel The Conceal Double Wall Book Shelf from Umbra mounts on the wall and becomes invisible behind a stack of books Constructed of powder-coated steel; mounting hardware included Supports up to 30 pounds of books; maximum stack height is 8 inches; available as a single, double, or towel shelf configuration Patent-pending, award-winning design by Miron Lior Size: 15.75 x 6.2" (40 x 15.7 cm)