Features a screw for exact diameter control, delivering professional levels accuracy for circles of all sizes. The polished surfaces ensures smooth operations and consistent results every time. Ideal for drafting, measuring, and precisions work. Simply rotate the top rings to open/close and adjust the diameter (clockwise to enlarge, counterclockwise to reduce). Create perfect circles in seconds without complex setup required. Perfect for quick sketches or detailed projects. The circular designs allows frees size adjustments to meet various drawing needs. Without extra tool needed.