Sacrificial zinc anodes are mandatory when using a Kasco motor in salted, brackish or highly conductive water. Sold individually.
Kasco recommends replacing zinc anodes annually or sooner if the anode is reduced by more than 50%. Zinc anodes are available for 1/2" and 5/8" motor shafts.
For 1/2" and 3/4" HP units, the shaft size is always 1/2". For the 1 HP units, some use 1/2" shafts and some use 5/8" shafts. So you need to measure the diameter of the rod to confirm which anode is needed.
In the diagram below, the anode is part B.
Watch this video to see how easy it is to change zinc anodes.