Mixed cellulose esters gridded membranes, sterile and individually packed, for colony counts in routine microbiological quality control. They are ready-to-use membranes and save preparatory time. The grid size is 3.1 x 3.1 mm. Available in various colours in order to ensure the best contrast to the colonies to be counted (white, black and green). Also available with hydrophobic edges. Hydrophobic edge membranes are used mainly in the sterility testing solutions containing antibiotics.