Sterile filter devices feature high quality membranes. To filter, attach the unit directly to the 50-ml centrifuge containing your sample, Flip it, and apply a vacuum. The filtrate collects directly in the attached 50-ml tube eliminating sample transfers between tubes. Disposable devices are sterile and have a 50-ml process volume. Warning: this product is not approved or intended for, and should not be used for medical, clinical, surgical or other patient oriented applications. For vacuum filtering solutions in 50-ml centrifuge tubes millipores express PES membrane is ideal for low protein binding and exhibits faster flow rates with viscous solutions.