Before the introduction of swing pipe, the standard way to connect a sprinkler head to an underground lateral pipe was with a rigid PVC or cut-off risers. Cut-off risers are preferred over rigid PVC when it comes to replacement because a single size riser can be cut to fit a multitude of different sprinkler head heights. The threads are in 1-in. increment sections so you can easily cut off a section of threads to achieve the height you desire. The cut-off riser extension allows you to put two or more risers together to form even taller risers. The inlets and outlets are in 1/2-in. and 3/4-in. versions which are common for flush head, spray head and rotor sprinklers. They are made from durable, UV-resistant HDPE. For non-constant pressure outdoor irrigation use with cold water only.