Conventional plastic slides used to test urine and other biological fluids frequently incorporate raised counting grids to facilitate the measurement process. These grid lines may rise from their base to as much as 10% of the entire height of the chamber. Vetriplast, from Vacutest Kima, provides a vast improvement over the conventional products since it utilizes a unique "patented system" of grid lines that are not raised at all but are flush with the base of the chamber. The liquid specimen added to the Vetriplast chamber encounters no obstacles which can interfere with the testing since the distribution of the elements on the reading surface is perfectly homogeneous.