Sierra 18-6011A Aluminum AnodeSierra replacement aluminum anode. Aluminum anodes are recommended for boats in brackish water, or if a boat is used in both fresh and salt water environments.Fits: Most Mercury/Mariner O/B's 35hp & above and all MerCruiser except BravoInterchangeable with: Honda Outboard; 41107-ZW1-003ZA; Mercruiser Stern Drive; 31640; 316404; 31640A1; 97-31640Q4; Mercury Marine; 31640; 316403; 316404; 31640A1; 31640A2; 31640A4; 31640B4; 72436A1; 97-31640Q4; Tecnoseal; 00800AL; 01411AL;