The chamber depth is 0.2 mm. The ruling differs from the customary systems for blood cell counts by its large area of 16 mm2. The ruling shows 16 large squares of 1 mm2. Each large square is subdivided into 16 mini squares with 0.25 mm side length and an area of 0.0625 mm2. This chamber is frequently used for counting cells in the cerebro-spinal fluid.