Abstract: A screening device limits the access of light to a viewing reference surface such as a computer screen. The device has a substantially opaque screening portion of predetermined size and form; and adjustable mounting means for attaching it. The device may have a shaped spine portion rotatably and slidably inserted in a mounting trough, which trough can be adhered to a support surface, such as the cabinet of a computer screen. Three such devices can form a hood about the top and sides of a screen. There are simple, non-adjustable embodiments. Use with a cell phone is contemplated.