6 unit (5 Counter keys and 1 totalizer). Totalizer carries totals to 999. Zero clearance knobs left and right. Bell signals each 100 key strokes for direct percentage reading of cell types counted. For more precise counts continue to 200 and 300 totalizer readings, dividing individual counters totals by 2 and 3 for percentage of each cell type counted. Mark cells counted on tabs provided.

Dimensions: 
9.8 x 3 x 2.2 in (25 x 7.6 x 5.6 cm)