Diver's Dream hull anodes with slotted holes eliminate the need for drilling and make it easy for divers to install them in the water.We offer these anodes in zinc, aluminum and magnesium alloys so you can select anodes for optimum protection against galvanic corrosion in the waters where you use your boat. Selection includes well known Divers Dream and Mini Divers Dream anodes. Divers Dream models are offered in 1/2" and 1" thicknesses.Zinc alloy anodes are for use in saltwater. Aluminum anodes protect better and last longer than zinc anodes when used in saltwater. Used in brackish water, aluminum anodes are also superior to zinc, which can passivate” and cease to work, and they are superior to magnesium anodes which corrode too rapidly. Aluminum anodes are also lighter than zinc and do not contain cadmium, a substance of environmental concern. Magnesium anodes also do not contain cadmium, and are for use in freshwater only.Key FeaturesManufactured to OEM and MIL-SPEC specificationsRigorously tested to ensure consistency and qualityZinc for saltwater onlyAluminum for saltwater or brackish waterMagnesium for freshwater onlyNote: Divers Dream in 1" thickness not offered in magnesium.