Determine longitude on protractor to determine course or bearingThe protractor's vertex allows placing a dividing point or pencil on a point of the holeA string can be used to fix the stopwatch used on the hole for a long distance of course.When charting, it is used to draw the bearing line or heading line, and measure the bearing line or heading degree.colour:TransparentMaterial:plasticsize:300mmPackage<br> Contents:4*Nautical chart drawing triangle rulerOnly the above package content, other products are not included.Note:<br> Light and different displays may cause the color of the item in the picture a little different from the real thing.<br> The measurement allowed error is +/- 1-3cm.<br> Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-DIMEANI official store