The 3M Petrifilm Flat Spreader is compatible with the following 3M Petrifilm Plates: Rapid Aerobic Count Plates, Rapid Yeast and Mold Count Plates, Rapid E. coli/Coliform Count Plates, Lactic Acid Bacteria Count Plates, Staph Express Count Plates, Salmonella Express Plates. Once the sample has been prepared, the top film is lifted from the 3M Petrifilm Plate to expose the inoculation area and the diluted sample is added. The technician places the film onto the sample then uses the spreader to distribute the sample. The clear acrylic construction of the spreader allows the technician to ensure proper inoculum distribution.