Jaw crushers are rated, or designated, according to the maximum dimensions of their feed opening, defined by the gape and the width of the plates. Feed openings can vary from 250 mm by 500 mm (10 in × 20 in) to 1524 mm by 2032 mm (60 in × 80 in). It is common practice to limit the largest particle of rock entering the jaw to be no more than 80% of the rated gape (Weiss, 1985).