Germany Opisometer Nautical Map Measurer Compass Inches to Miles CM to KM

This is a German Opisometer.

This metal and glass nautical instrument has a compass on one side for directions of travel, and using the wheel on the stem it converts inches to miles and centimeters to kilometers to measure distances. The other end has a twist-out pencil.

The tool measures 4.75" long and 1.25" wide.

It is in good preowned condition.