Honeywell Pentax 3 degree / 21degree Exposure Meter
This is the original model, sold as is, untested. I don't believe you can find the batteries anymore. Still amazingly cool. Case is a bit beat, but strap is good and meter is very clean, lens and finder perfect images
The original manual is here
https://www.cameramanuals.org/flashes_meters/pentax_3-21_exposure_meter.pdf