Isomars Set Squares - Technical - Set of 5 Drafting Rulers are combination of 10" and 12" professional triangles, Scale - 12" & ProCircle made of clear plastic And Mechanical Pencil 2mm. Set Squares are used in conjunction with straightedge of drawing board to draw accurate angles. Bevel. Markings on both side in cm/inch.Non slip grip for daily writing. It is the suitable tool for sketching and drawing. Superior drafting pencil for general and technical writing. Comes with eraser.