Whatman® Carbon Air Filter, Grade 72 Activated, 5.5cm Circle. Whatman offers two types of glass microfiber filters manufactured from 100% borosilicate glass: binder free that is chemically inert and with binder. These filters combine fast flow rates with high loading capacity and the retention of very fine particles, extending into the sub-micron range. Can be used at temperatures up to 500°C and are ideal for use in applications involving air filtration and for gravimetric analysis of volatile materials where ignition is involved. They have a fine capillary structure and can absorb significantly larger quantities of water than an equivalent cellulose filter, making them suitable for sport tests and liquid scintillation counting methods. Can also be made completely transparent for subsequent microscopic examination.