Add 6 in. of height to a traditional valve box with the stackable 14 X 19 in. Rectangular Standard Series Valve Box Extension and Cover. The riser and lid can also be used to cover and protect underground irrigation and sprinkler systems in shallow installations. The purple overlapping cover prevents dirt and debris from entering the valve box and is marked "RECLAIMED WATER" for content identification. The edge of the cover also indicates where to lift. The irrigation valve box is made of polypropylene (PP) and the lid is made of high-density polyethylene (HDPE), both treated with UV inhibitors