Aluminum Alloy (US MIL-A-24779(SH): For use in salt and brackish water Not recommended for use in fresh water Proven to last longer than zinc due to increased capacity Alloy is manufactured to meet or exceed US Military Specification (MIL-A-24779(SH)) Contains 1 x CM762144 1 x CM762145 1 x CM865182C 1 x CM821630 2 x CM806190 If you are unable to see the size anode you need, please contact us for assistance