Wagner Ware Double Stack Roaster?

[BenjaminO]

Hello CIC folks, I've been away for a while but have come back to share this unusual item I found.
It's an early cast aluminum Round Roaster top and bottom marked 248 with a middle section that has a false bottom.
I'm curious what the correct name, intended use, and approximate value of this thing is. Other than some light surface corrosion here and there and some staining in the bottom this thing appears to be in completely restorable condition.
Thanks for any information.
DSCF0560 by Refinders, on Flickr
DSCF0561 by Refinders, on Flickr

[Doug D.]

It doesn't appear in the 1924 catalog, but does in the 1927, in a section titled "Cooking Without Water", in which are featured several new offerings in cast aluminum. This item is called a "Combination Cooker". It appears to be the only size offered, and was gone by the time the 1936 aluminum catalog was published.

[BenjaminO]

I'm having trouble imagining how you would cook in this thing. What would go on that level 2 plate? something dry, as any liquid would drain to the lower level, but then it would only be warmed to steam temperature from below. What in the world do you bake at 212 degrees or less?

[Doug D.]

..............

[BenjaminO]

Any guess as to what it could fetch at auction?