These GF/A glass microfiber filters have a reinforced outer perimeter and offer fine particle retention and high flow rate, as well as good loading capacity. Used for high efficiency general purpose laboratory filtration, including water pollution monitoring of effluents, for filtration of water, algae and bacteria cultures, foodstuff analyses, protein filtration and radioimmunoassay of weak ß emitters. Recommended for gravimetric determination of airborne particulates, stack sampling and absorption methods of air pollution monitoring. Retention: 1.6µm. Diameter: 6.0cm. 100/Pack. Whatman #: 1820-061.