HIGH QUALITY COMPASS We have all tried using a cheap plastic compass that cant hold the shape for even a single circle and forces you to have to try again. With this high quality Ferocious Viking bow compass you will not have that problem. The set screw in the center of the compass allows you to accurately set the size of the circle you need and hold it.VERSATILE An Extension Beam attaches to the big Ferocious Viking Bow Compass for drawing large circles and arcs up to 22 inch diameter, very useful for those times you need to think BIG.EXTRA FEATURES Includes a sharpener for sharpening the point of the lead to always be able to create precise arcs and circles. Also includes a small container for lead, so you have a replacement handy when needed. Additionally includes a small stylus pen that can be used in the slip handle or separatelyIDEAL FOR MATH CLASSES Such as Geometry class, drafting, architectural drawings, engineering designs, both mechanical design and construction. It is a necessary tool for bisecting angles, constructing geometrical shapes, including perpendicular lines, parallel lines, triangles, circles, rectangles, pentagons and virtually any geometrical shape.