3M DH640 Free Standing Document Holder Innovative, centerline-position design of the DH640 In-Line Document Holder helps reduce head, neck & eye movement. Versatile angle & height adjustment for easy viewing. 18" wide clear backplate keeps monitor in full view. Holds books, catalogs, & landscape documents. Elastic Line Guide expands to hold thick documents & catalogs firms in place. Weighted base safely supports large documents & books. Non-slide grooved shelf with raised edge keeps large, oversized documents secure.