iPod Classic 6th Gen ("7th Gen"/MC297) - What material is used for the metal back plate?

Hi All,

Hoping someone can provide me with what specific material the metal back plate of the iPod Classic (Model MC297) is made from - i.e Some Alluminium Alloy, Chrome Plated, Stainless Steel? And in each case what grade or category the material is - i.e 301 grade Stainless Steel, V1341 Alloy etc.

So far I haven't been able to find much on the material specifications of this part - so any help would be great.

And FYI - Specific material specs are "required" as I'm trying to customize the back plate through some process like heat treatment of anodization/dyeing.

Thanks in advance,

L.