The pendulum is mounted on antifriction bearings. It has two starting positions, the upper one for Charpy and the lower one for Izod testing. On release, the pendulum swings down to break the specimen & the energy absorbed in doing so is measured as the difference between the height of the drop before the rupture of the test specimen and is read from the maximum pointer position on the dial scale. The Charpy test piece rests on alloy steel support anvils, fitted on the base of the machine rigidly held in position by Allen screws. An end stopper is provided for quickly and accurately locating the test piece centrally between the supports.