Two tray shaped, metal platforms connected by two spring metal blades comprise the inertia balance, 33 L X 10 W X 1.8cm H. One platform is clamped to a table top, and the other can oscillate clamped to a horizontal plane. A solid cylinder of plated steel, 10 X 2.5cm with hole and pin arrangement to suspend it form the balance, is included. A hardboard sheet, 10 X 10cm; a length of cord; and paper clips also included. A G-clamp, our no. 2045A, is recommended but not included.