"Rock armor" redirects here because Americans spell "Armour" "Armor."
A search for "Rock armour" on google returned about 32,000 results today, and one for "Rock armor" only returned 10,000, and some of those where caused by a plastic product called "Rock armor," which is why I have left "Rock armour" as the standard spelling, and made "Rock armor" a redirect to it (and not the other way around).
See also the Rock armor talk page