One frustrating thing about is that for years, GE simply called these the "GE Exposure Meter." Model numbers wouldn't show up until the 1940s, and even then, not in advertisements until they began selling different models simultaneously. I suppose it was cheaper since they could run their advertising separately from engineering, and simply send out a new version of the meter without having to deal with model designations. But it makes collecting and identifying a pain in the ass.

This is a DW-47; I know because it's marked on the meter face in the lower right corner, but you have to open up the works to see it: the cutout for the face covers it up.

I believe this is the first of the DW series. It's case is plastic (I believe Bakelite) and the top slides down to cover and protect the meter face. You pull the cover up and click it into position to make readings. There's a grated, hinged flap on the top for high/low light levels. You could also pop the top off entirely for incident reading, but the calculator dial has no calibration for it.

Subsequent models ditched the plastic in favor of metal housings which take a lot more abuse. The hood was fixed into place and the meter face left exposed. I believe that these DW-47s probably broke too often (the hood on this one shrunk a little and no longer slides up and down. It's stuck permanently in present position) and GE changed it to reduce breakage. It must have worked: I rarely see these early bakelite models, but the metal-clad versions are all over.