Most water heaters have an in-built anode rod to protect the unit from breaking down internally. These anodes should be replaced when the unit has degraded more then 75% which should be checked annually, depending on the amount of water used.

FEATURES
Protects your water heater
Improves water quality
Designed for suburban RV water filters
DIY Installation
241mm long 3/4" NPT Thread

SPECS
Thread: 3/4" NPT
Length: 241mm