Vintage analog instoscope lightmeter.
Here we have a lightmeter of a different sort. According to www.camera-wiki.org "The Drem Instoscope was an extinction meter in. When viewing thru the ocular one could see a number of letters. The least visible letter was explained on the table which was wrapped around the instrument. The table showed the possible shutter-speed/aperture combinations for the least visible letter." That's how it works. This one works, there's not much to it, just look through it, adjust by pushing in or pulling out, read the letter, and reference the chart on the outside of the device. Comes with a leather case.