Usage Tips:plot accurate bearings or course lines with this 12 inches parallel ruler; Using to plot lines of bearing or course, degrees of a bearing line or degrees of a course before charting, this tool combines the basic functions of a protractor plotter and a basic parallel ruler, it brings convenience to meridian measurement routes; Making it ideal for use in various environments, including boats and ship embrace the longevity that this parallel ruler marine offers thanks to its construction from quality acrylic material with brushed aluminum arm and polished aluminum handle; The use of quality material ensures durability, coupled with long lasting service, standing up to the test of time even under frequent use the scales of our navigation parallel ruler are clear and easy to see; It is engraved with full 180° protractor markings; When the arms are closed, the middle of the bottom edge forms the protractor center, ensuring you have all the tools you need in one compact design this parallel ruler navigation boasts a good transparency to ensure unobstructed viewing of information during use; This feature significantly improves your user experience, making for smoother, more accurate mapping and drawing you just need to hold the marine navigation parallel ruler in each hand and move parallel to each other alternately; Sturdy connector with appropriate tension can be applied parallel to another ruler or as a reference, ensuring your parallel drawing process is not just correct but also enjoyable Colour:As Shown Material:Metal Package Contents: 1 x parallel ruler Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.