Mixed cellulose ester membranes are suitable for microbiological analysis of water, wastewater, pharmaceuticals, or beverages. Offered with or without grid lines; grid lines facilitate counting colonies on the membrane surface. Grid squares measure 3.1 mm and represent 1/100 of the area of a 47-mm membrane. Black membranes maximize contrast between colonies and the filter; green membrane enables viewing of black, white, and colorless colonies on a single filter. Presterilized by EtO, these 47-mm diameter filters are available in envelopes of 10, individually packaged, or now individually wrapped continuous feed. Order membranes with absorbent pad for use with broth media.