4105-1 Size: 12" Features: -Set include the shaft, anchor point, lead holder and lead all in one package.-Solves the problem of making perfect large circles up to 24" diameter.-Beam compass attaches to thin profile yardsticks and automatically shows figures for the radius circumference and area of any circle in inches or centimeters.-Adjust circle size with fingertip control.-Calibrations in inches on one side and metric on the other.-Dimension: 0.12" H x 2.25" W x 12" D.-Dimension: 0.12" H x 1.25" W x 18" D.