A cover system for a substantially flat support surface on a vehicle includes plural removable panels configured to be disposed at opposite lateral sides of the support surface, lower supports which support lower surfaces of the panels and upper rails which retains upper surfaces of the panels at the opposite lateral sides of the support surface. Edge portions of the panels are shaped to overlap with the edge portions of adjacent side panels such that outermost surfaces of the panels extend substantially continuously when the panels are operatively disposed at the opposite lateral sides of the support surface. Each of the panels includes retaining device selectively fixing a lower portion of the panel on the vehicle.