Features: 1. Magnesium rod is also called anode rod, the main component is magnesium. 2. In the inner tank of the water heater, it is in contact with water at the same time as the inner tank (mainly iron), and the primary battery is formed due to chemical principles. 3. Since the water in the inner tank is not pure water, it always contains various impurities and has certain corrosiveness. When the water temperature exceeds 40 C, scale will be generated. If there is no magnesium rod, the inner tank will be corrosion. 4. The basic function is to prevent corrosion and scale, and to protect the liner. 5. Main use: large hot water tank liner anti-corrosion for car and car water heaters. Specification: Condition: 100% Brand New Item Type: Water Heater Anode Rod Product Material: AZ31B Environmental Magnesium Alloy Product Standard: EU Environmental Standards Size: Approx. 21 * 235mm / 0.8 * 9.3in Color: Black Thread: NPT3/4 Package List: 2 * Water Heater Anode Rod 1 * Tape Note: 1. Please allow slight error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.