The Whatman Anotop 25 Plus syringe filter offers the added benefit of an integral glass microfiber prefilter. This unit is designed to enable difficult and hard-to-filter solutions to be filtered without adversely affecting the filtration efficiency of the final membrane. This can eliminate the need for sample cleanup or expensive and time-consuming sequential filtration. Made from Gamma-Alumina 6mm Al203. Medium protein binding. Diameter: 25mm. Sample volumes up to 100ml. Non-Sterile. Retention: 0.2µm. 50/Pack. Whatman #: 6809-4022.