Extra Shelf, Color Light Gray, Load Capacity 150 lb, Number of Shelves 1, Overall Depth 18 in, Overall Width 36 in, Product Type Shelf, Adjustable No, Compatible Manufacturer Model Number BC18-30, BC18-30M, BC18-42, BC18-42M, BC18-52, BC18-52M, BC18-72, BC18-72M, BC18-84, Compatible Product Type Bookcases, Overall Height 3/4 in