Circle Brand muffin pans

These metal muffin pans are about 6.5" square with cups that are 3" x 1.25". There is a logo in the center which says "Circle Brand Copyrighted". Not sure if they are steel or tin. I think they have quite a bit of age, maybe 1930s? It is odd that they say "Copyrighted" as opposed to "Patent Pending", "Patented" or "Trade Mark", I think.

Because the writing is inside three circles that seller called them "Three Circle Brand" but that was just a guess. I found a couple of other examples on line, but nothing about the brand. I have been looking for some for muffin pans that will fit into my toaster oven and came across these. I use my natural gas oven for storing cast iron cookware, and it is a bear to unload it all just to use the oven, so I just stick to my toaster oven.

As a twenty year anniversary gift from my ex-employer I got a large, fancy countertop convection oven, but have never taken it out of the box. My 20 year old toaster oven does everything I need, although it is small.... Does anyone know anything about "Circle Brand" cookware?

Update: I have now used these in my old toaster oven and they work great! My new toaster oven is out of the box, but I have not tried to use it, yet as it is a tad more complex to use than my old oven.

Still not found out any more about the maker of these muffin pans. These are very sturdily constructed so there are many examples to be found on online auction sites.