Abstract: A plurality of plastic panels or planks (12) are connected to each other in side by side relation by interfitting male and female connectors (28, 30) to form a planar structure such as a cover (10). The male connector (28) has opposed outer planar surfaces (32, 34) in contact relation to opposed inner planar surfaces (46, 48) on a female connector (30) to minimize any relative pivoting or articulating movement between adjacent panels (12). Adjacent panel sections (15A, 17B) are hinged to each other about hinges (35E) to permit the panel sections (15A, 17B) to be folded against each other for stacking. Alternatively panels 14C, 14D may be linked together for stacking. A side support (16) is secured to the sides of the cover (10) to cover and to support a side of a panel where such side is not connected to another panel.