Size and Material type: Magnesium anode rod, 4.5"Long, 0.5“diameter, 1/2" Threads. | Extends the life of a water heater by attracting corrosive elements in the water. If the anode rod is depleted and fully decayed, the water heater will begins to rust, then crack, fail and leak. | Made using high-quality magnesium. Our magnesium rod absorb oxidizing substances and all the contaminants in the water towards itself by electrolys, preventing the water tank from rusting in the metal water tank, ensuring your RV water heater lasting use. These water heater magnesium anode rods work better than aluminum ones in attracting corrosive elements, protecting your water heater and prolonging its life span with little to no investment. | For use with: Atwood water heaters | Pack of 2: Unscrew the anode rod to drain the tank. If the rod is mostly eaten away, replace with a new one. Always keep a spare in your RV.