flipper with spherical lenses +/- 0.25 to perform ROCK ACCOMODATION exercises, i.e. to develop the ability to move the point of focus quickly and accurately from close range while maintaining good eye coordination - the exercise enables the development of adequate flexibility of accommodationin the subjective examination this flipper is also used to test the increase in sharpness at the start of the visual examination in cases where the data available at the start are not sufficient to assume ametropia