Function: Aligns the center of the protractor at the edge of the ruler with the vertex of the measuring angle, and make the scale line of the protractor coincide with the reference line. It can measure and draw various angles at the edge of the ruler. Brush and curved curve: Insert the pen into the small hole at the end of the ruler as the center of the circle, insert another pen into another hole, and rotate the ruler body a total of 360 degrees to draw a circle. Draw a horizontal parallel line: Place your hand on the ruler, draw a horizontal line along the edge of the ruler, and then move it. Plastic: The parallel ruler is made of plastic, durable and wear-resistant. Transparent design: The drafting roller ruler adopts a transparent design, with clear scales and easy to use. Specification: Material: Plastic. Color: As shown Size:Approx.30cm/11.81inch Approx.15cm/5.90 inch. Package Includes: 1 Piece Angle Ruler.