White 1+PAC White gridded discs are designed for the recovery and retention of E. Coli bacteria in water / waste-water analysis as well as other microbiological tests. The 1+PAC is also ideal for sterility and bioburden testing in QC/QA laboratories. Black 1+PAC GVS offers black MCE filters specifically manufactured and tested for quality assurance testing in food and beverage analysis. Without proper microbiological testing, the taste, odor, and appearance of the final product can be ruined, resulting in lost production time, expensive in-line cleanup, and end product loss due to spoilage. The black filters provide a superb contrast for early and accurate colony counting for total bacteria, yeast, and mold organisms.