The Maped Precision Bow Thumbwheel Compass is perfect for advanced geometry and drafting classes – easily draw up to a 13″ circle! The Thumbwheel adjustment system gives you incredible control over the diameter of the circle you’re drawing, and the durable metal legs will last for years. Universal holder attachment works with all standard pencils, pens, and fine tipped markers and is easy to swap out with the included classic compass lead attachment. Compass set comes with Precision Bow Compass, Universal Holder Attachment and replacement compass lead packed in a reusable, shatter-resistant case. Compass comes in 3 assorted colors (Green, Blue & Purple).