Koala Tools | Ring Ruler 360 - Circle Stencil & Templates Tool | 3"- 6" Adjustable Diameter - Geometric Tool for Drawing Circles ADJUSTABLE CIRCLE CREATION: Mathematical ruler that creates perfect circles seamlessly in seconds. 3 to 6 inch diameter range. SCHOLASTIC & CRAFTY: Handy for kids and students at school as a 360 degree protractor. Ideal for sculpting, woodworking, quilting, sewing, and gourd design. HIGHLY VERSATILE: Works with lead pencils, pens, markers, or airbrush. Usable on either flat 2D or spherical 3D objects (vases, bowls, ornaments). DURABLE CONSTRUCTION: Sturdy plastic remains strong yet flexible for circular drafting or cutting arcs and curves. PRECISION CALIBRATION: Measures diameter, arc lengths, and circumferences with extreme accuracy.