Multifunctional Rolling Ruler The 12 inch multipurpose ruler is ideal for designers, artists and students. It functions as a compass, horizontal ruler, straightedge, protractor, circle template and angle template all in one. Measures in inches and centimeters and includes many useful formulas and conversion factors. Quick and easy draw in quadrants, squares, circles, angles, crosshatching, vertical and horizontal parallel lines. How to Use: The use of protractor: Align the center of the protractor on the edge of the ruler with the vertex of the surveying foot, and at the same time, coincide the scale of the protractor with the datum line, then various angles can be measured on the edge of the ruler. To Draw the Arc and Curve: Insert the pen into the small hole at the ruler end to make the center of the circle, insert another pen into another hole and rotate the ruler body 360°to draw a circle. If the radius between the 2 holes is different or the rotation ruler body is different, different circles or arcs can be obtained. To Draw Horizontal Parallel Line: Press your hand on the ruler body, draw a horizontal line along the edge of the ruler, and then move the ruler up and down to draw a parallel line. To Draw Vertical Parallel Line: Insert the pen into the small hole on the edge of the ruler, slide the ruler up and down to draw a vertical parallel line. The distance between the vertical lines can be measured directly. Specifications: Material: Plastic Color: Clear Length: 12 inch Width: 2.4inch Package Included: 1 x Measuring Rolling Ruler 1.The color maybe tiny different from the picture because of the photograph. 2.Please allow a little bit of size deviation due to manual measurement.