Stainless steel holders differ in their funnel capacity (choice of 40 ml, 100 ml or 500 ml) and in their valve type (part numbers ending with CS feature sterile venting). They are specifically designed for applications in which particles or microorganisms need to be retained on the surface of membrane filters. Their stainless steel frit filter support ensures uniform distribution of the retained particles over the entire surface of the membrane filter. Special features facilitate the use of these filter holders during routine testing. Their stainless steel taps are easy to turn on and off, and only one hand is needed to use the unique clamp for secure fastening or convenient removal of the funnel.