Abstract: An improved sheathing for use as a covering on a polygonal container having a plurality of adjustable support members for supporting the sheathing thereon. The sheathing comprises at least two adjacent pivotally connected panels having a vertical joint therebetween formed by an offset edge of one panel overlying an adjacent edge of the other panel. The panels include a mechanism for adjusting the angle between the panels comprising a pair of pivotally connected plates, each of the plates being pivotally connected to a respective one of the panels, and an adjusting screw threadedly mounted to the plates and extending towards the joint.