Features a screw for exact diameter control, offering professional levels of precision for rims of all sizes. Glossy surfaces ensure smooth operation and consistent results every time. Ideal for drawing, measuring and precision work. Simply twist the top rings to open/close and adjust the diameter (clockwise to enlarge, counterclockwise to reduce). Create perfect circles in seconds without the need for complex setups. Perfect for quick sketches or detailed projects. Circular designs allow you to freely adjust the size to meet various drawing needs. No additional tools required.