The NDS STANDARD SERIES 10" round valve boxes and covers are injection molded of structural foam polyolefin material with a melt index between 10-12. Coloring and UV stabilizers are added, along with processing lubricants when needed. The 10" round cover shall have an average thickness of .187".
Overlapping covers prevent dirt and grass from settling between body and cover
UV inhibitors prevent discoloration and deterioration; such as cracking or blistering