These nipples are threaded pipe fittings in schedule 80 PVC (polyvinyl chloride). Schedule 80 risers are threaded on both ends. Schedule 80 risers are a very common component in most lawn sprinkler irrigation systems. Schedule 80 is also NSF listed, has a 140 degrees Fahrenheit working temperature, and is available in gray. For UV resistance of PVC pipe and fittings, paint with a white water based latex paint. Use thread lubricant or PTFE tape on threaded joints. Replacement for model Dura 8507, Ewing 044005620, Lasco 215-040, Spears 886-040, PVC fittings direct 8150-040. Available in gray color. Measures 4-inch length by 1-1/2-inch diameter.