Features: There are 2 types, one is 20cm/ 8 in, another is 30cm/ 12 in. Simply tap a small nail or pin (not include) through the center hole, insert a pencil in your choice of diameter hole, and pivot around the center point to make your circle mark. With laser scale, the round center finder compass is clear to read and not easy to get dirty or damaged, Before use, please tear off the film on the reading, so that you could see the reading more clearly and more convenient for you to use. Made of high quality acrylic material with a central hole and clearly marked circles, which allows you to see exactly what you are doing and helps you measure quickly and easily. Can be applied wherever a circle is needed, fits for wood turning, art, crafts, school projects and finishing woodworking; For wood, poster boards, plastic, metal, glass, composite materials, etc. Package Includes: 1X Circle Center Finder Specifications: Material: Acrylic Diameter: 20cm/ 8 in , 30cm/ 12 in note: Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item.