The Camco RV Anode Rod with Drain is a sacrificial rod that extends the life of your water heater tank by absorbing the corrosion causing particles in the water. As a result, the water corrodes the rod rather than your water heater tank. This anode rod is compatible with Atwood-style aluminum water heaters. The 5/8" OD magnesium anode rod measures 4-1/2" long and has 1/2" NPT threads. It features an internal drain valve, allowing you to drain your water heater without tools. Compatible with Atwood-style aluminum water heaters 4-1/2""L x 5/8"" OD magnesium anode 1/2"" NPT threads