An advertising display unit adaptable for attachment to a guard structure such as upright supports located adjacent the fuel pump islands associated with a typical service station, the present display unit including a sign structure having a pair of generally opposed display panels positioned in spaced apart relationship so as to form a cavity adaptable for receiving the guard structure. Each display panel includes an attachment structure for removably securing the sign structure to the guard structure so as to retain the display unit in a generally upright orientation. In a preferred embodiment, the attachment structure includes a plurality of openings associated with each display panel and a plurality of tie members or cable straps positionable through selected openings for pulling a portion of each display panel into engagement with the guard structure.