PRACTOS EXTINCTION LIGHT METER FROM GERMANY 1930S
The earliest light meters were called extinction meters and didn't require batteries. They worked by looking through their viewfinder at a small strip of letters that were progressively darker. The darkest letter you could just barely read was your light value. You then used the handy barrel to convert the light value to your exposure, taking into account the sensitivity of your film emulsion.
This meter is calibrated in Scheiner degrees and not ASA. It has allowance for filter factors (2x, 4x, 8x), the apertures are geometric (f/1.4, 2.0, 2.8 up to f/22), but the shutter speeds are old-style (1/2, 1/5, 1/10, 1/25, 1/50 up to 1/1000).
It was made in Germany by the CHD Company and comes in beautiful condition ensconced in it's own little leather case.