The variety of alloys utilized is spectacular: weathering steel for patina, marine-grade aluminum for weight savings

https://www.scribd.com/document/1042029003/The-Heritage-of-Hand-Fabricated-Metal-Customized-Leader-Boxes-Designed-to-Endure-a-Century-198695

The series of alloys used is sensational: weathering steel for aging, marine-grade aluminum for weight financial savings, and duplex stainless for rust resistance in harsh environments.