3/4″ MNPT Replacement Magnesium Anode. Installed in every water heater, a magnesium anode, also known as a sacrificial anode, is a noble metal that corrodes instead of the inner tank. Having it in the tank is important for the integrity of the tank.
The Sunbank tank is made of high quality stainless steel, which is the most durable of the commonly used water tank materials. However, every metal is eventually susceptible to corrosion. How often you need to change the anode depends on local water quality. It should be checked after one year of operation to see the rate at which it is corroding. If half of the anode remains you should change the anode at least every two years. If 2/3 of the anode remains you should replace the anode every three years, etc.