Useful to measure long distances or demonstrate the relationship between circumference and diameter. The circumference of the wheel measures an accurate meter, and an audible, nonwearing clicking device is activated in either direction with each 1-m revolution. Wheel edges grip smooth surfaces, preventing slippage as the wheel rolls. A sturdy, plastic handle enables the user to walk while rolling the wheel. The scale is graduated in 1-cm divisions. Approved by the Canadian National Metric Council.