UltraCruz® Bottle Top Filter with PES (polyethersulfone) membrane is a device that attaches directly to a container, bottle, or vessel in conjunction with a vacuum source for sterile filtration of large volume aqueous samples. With low protein binding and low extractables, PES Bottle Top Filters are used to separate and purify cell culture media, serum, and HPLC solutions. Bottle Top Filters are sterilized by gamma irradiation making them nonpyrogenic, noncytotoxic, and RNase/DNase free. The low liquid retention funnel design supports a high flow rate. They have engraved graduations that allow for precise work. Filters also come with a 0.22 µm pore size and a polyethersulfone (PES) filter. They are manufactured from U.S. Pharmacopeia (USP) class VI virgin polystyrene in a class 100,000 cleanroom. Class VI is the most rigorous testing aimed to certify that there are no harmful reactions or long-term bodily effects caused by chemicals that leach out of plastic materials. Class 100,000 cleanrooms are allowed a maximum of 700 particles per cubic foot greater than 5 microns and less than 100,000 particles per cubic foot greater than 0.3 microns. Bottle Top Filters must also have at least 20 air changes per hour. This classification is closest to ISO-8 by the International Organization for Standardization. Bottle Top Filters are compatible with UltraCruz® Solution Bottles.