Comprises a 50-0-50cm meter rule graduated in millimeters with an adjustable knife edge that rests on a stone agate to form the fulcrum. On either side of the fulcrum, a knife-edge clamp is located to suspend mass hanger. By adjusting the position of weights along the meter rule, to students can study the law of torque for different centers of rotation, measure various lever arms to compute corresponding torques and compare clockwise and anticlockwise torques. Complete assembly supported on a base. Includes two mass hangers and 8 slotted masses from 1g to 500g..