Right on the box it says "Anodized Aluminum", after a bit more work I decided that they are actually 'hard' anodized. "Hard-anodization is an electro-chemical process that hardens the surface of the aluminum. (Hard-anodized aluminum is 30% harder than stainless steel). During hard-anodization, aluminum is submerged in an acid bath and then subjected to electrical charges. The result is a chemical reaction where the surface of the aluminum combines with oxygen to become aluminum oxide. This reaction is also known as oxidation, a process which occurs spontaneously in nature. Hard-anodization is actually controlled, accelerated oxidation." Does that really say 30% harder than stainless steel?, no wonder. They use this process on aluminum used on satellites to protect it from the harsh environment of space!



Link: PimpRig