RTF: Some of our Al anodes are made by Performance Metals, (thanks jjanack for the reference). Here's what they say:
"The aluminum alloy used in Navalloy anodes is very different from normal aluminum. It includes about 5% zinc and a trace of Indium, which prevents the build up of an oxide layer".
"The aluminum alloy used in Navalloy anodes is very different from normal aluminum. It includes about 5% zinc and a trace of Indium, which prevents the build up of an oxide layer".