These anodes are made with an aluminum alloy which is specially formulated for marine anode use.
They last longer than zinc anodes and, utilizing a less toxic activator, are safer for the environment. TD-S has a single and a slotted mounting hole for 1/4" fasteners. With the slot, it has a 1-5/16" to 1-5/8" center-to-center mounting stud range.
TD-L has a two slotted mounting holes for 1/4" fasteners. With the slots, it has a 1-9/16" to 2-9/16" center-to-center mounting stud range.

Affords protection in brackish as well as salt water
More economical than zinc anodes
All Sea Shield aluminum anodes conform to Mil Spec MIL-A-24779 for maximum protection
Less than half the weight of comparable zinc anodes
Made in California, USA