The fine particle retention of this popular grade is superior for its high retention efficiency at high flow rates and its high loading capacity. This filter is a smooth surface high retention borosilicate glass microfiber which withstands temperatures over 500°C. Specified in Standard Methods 2540D for determining total suspended solids in water removal of turbidity and filtration of bacterial cultures. Grade 934-AH is used for a wide range of laboratory applications. It is recommended for water pollution monitoring cell harvesting liquid scintillation counting and air pollution monitoring. Retention: 1.5µm. Diameter: 4.25cm. 100/Pack. Whatman™ #: 1827-042.