NDS 13" x 20" meter boxes and covers are injection molded of structural foam recycled polyolefin material with a melt index between 10-12. Coloring and UV stabilizers are added, along with processing lubricants when needed. The 13" x 20" body is tapered and has a minimum wall thickness of 0.250". The body has a double wall at the top cover seat area with a minimum thickness of 0.187". The cover seat area has 30 structural support ribs on the underside of the seat, each with a minimum thickness of 1/50". The bottom of the body has a 1" flange. The 13" x 20" cover has an average thickness of 0.250"