Interesting. That's only the second time I have seen it. Note, though, that it doesn't technically say "aluminum plating", whereas the "bright plate" option is more explicitly a plating, and usually a reference in Vlchek publications lingo to chrome. The reference to "aluminum finish" could be some other kind of coating.
In the 1936 and 1941 catalogs, the available finish options for various Vlchek end wrenches were "Bright plated" (for their high end, again, ostensibly chrome), "Velco" (for their "cheaper, but equally serviceable" economy lines, and while I have never been able to find a TM or compositional description, almost certainly a reference to cadmium), sometimes more elaborately called "Velco Rust Proof" and "Velco White Rust Proof", "Natural" (self-explanatory), "Japanned", and "Black enamel."
Except for the 4-way rim wrench. That was available in "Velco Rust Proof Finish", "Aluminum Finish", "Black Japanned Finish", and "Natural Black Finish", and, note, in descending order of cost. Whatever the "aluminum" finish was, I don't think it was plating.
Lastly, whatever it was, it would've been banned during WWII. And it does not re-appear in 1949.