54 in. by 0.9 in. Diameter Flexible Magnesium Anode Rod for Electric and Gas Water HeatersAnode rods are the most important line of defense in preventing corrosion and leaks in your water heater. These devices work because the metal in the rod is sacrificed so the tank does not corrode. As the anode works, the life of the water heater is increased. The anode should be checked and replaced every couple of years. This 4 section Rheem PROTECH anode is 3 4 in. NPT X 54 in. California residents see Prop 65 WARNINGS Fits many brands of water