Add height by stacking the 14 X 19 in. Rectangular Standard Series Extension Box on top of a traditional valve box or use alone to cover and protect irrigation and sprinkler system components in shallow installations. The black riser is 6-3/4 in. high and adds 6 in. of height when nestled in a 14 X 19 in. Valve Box. The enclosure is built with reinforcing ribs for durability and made of polypropylene (PP) treated with UV inhibitors