The Professional Protractor Triangle with handle is larger than other navigation triangles on the market with legs that are 9. 312 inches long and a hypotenuse (long side) 13. 125 inches long. It has both 320mm & 1-80,000 scales and is constructed of heavy duty clear 5 mm thick acrylic for durability with a handle for ease of use. Both pencil and pencil sharpener are included with the Professional Protractor Triangle and this product is backed by our lifetime warranty. - 1. Slide two triangles to transfer course or bearing. - 2. Place protractor vertex over meridian of longitude to determine course or bearing - 3. Hole at the vertex of the protractor allows the point of the divider or pencil to be placed on a meridian for a