The 1/2 in. valve was used on Atwood water heater models manufactured before February, 2006 and can be identified by the orange thread protector. Newer models require a 3/4 in. valve with the red thread protector. Priced each.
Water Heater Parts
Prop 65 Warning
WARNING: This product may contain one or more chemicals known in the State of California to cause cancer and/or birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov