[aloppoct]

Jim, you are so right calling it pre-rusted steel. It is probably CORTEN, by U.S. STEEL. They were the first to fabricate what is now commonly called weathered steel. Others such as MARY-R came later.

[TheConservativeTejano]

Partner, this is because it is CORTEN type steel structure material. It is very reliable steel material and it is pre-rusted but it will never destroy itself since you do not have to paint or galvanize this material ever again.