This product is a round protractor, the swing arm can slide 360 degrees without dead angle, which is more convenient for teachers to demonstrate right angles and obtuse angles for students. This tool also helps students to standardize drawing. Features -Material: ABS -The plastic protractor's swing arm can rotate 360 degree, which makes you measure and draw angles and length accurately. -High definition printing, wear-resistant and color-resistant. Independent packaging, easy to carry. -The arm is easy to swing from side to side, thus convenient for teachers to demonstrate to their student. - ruler protractor set is suitable for measuring, painting, technical drawing, homework, etc. -Easy-to-read with the clear scale. Great studying tool for student, it will help them learn more. Package list: 3 x Plastic 360 Degree Protractor