The unit is performed as a basement on height adjustable supports. A vertical rod is fixed on the basement. A bracket with an inclined plain fixed by means of joints is mounted in the upper part of the rod. Replaceable plates are mounted on the inclined plain. A ball fixed on a flexible suspension is moving on the plates. A photosensor registering the number of oscillations is also installed on the inclined plain.
An electronic stopwatch is used to fix the time of the pendulum oscillations.