材质：安全塑料；以滚轮尺帮助学生测量长距离的尺寸，
1 圈代表1 公尺可测量操场、或是教室的尺寸。
Accurately counts to 9999 metres, or it can be set to register every 10cm to a maximum of 999.9 metres.This robust counter presents the opportunity to extend the activities of the Trundle Wheel.Designed to fit in place of the standard clicker.
