APR's Douglas International Navigation Combination Protractor and Parallel Rule Plotter
includes operating instructions to lay out a course bearing, use as a parallel rule, find departure or latitude between two positions or magnetic course or bearing from true, and to plot lines of position.
WAC/ONC 1:1,000,000 VIS/TERM 1:250,000 Scales. PVC plastic
Dimension: 5" x 5"