Kasco recommends replacement of zinc anodes every year or sooner if anode is more than 50% depleted.Zinc anodes are available for 1/2 in. and 5/8 in. motor shafts.Key FeaturesFor 2400 & 3400 De-Icer modelsShaft Size: 1/2"Height: 1 1/4"Base Diameter: 1 1/2"Hex Wrench: 9/64"