The fastest ashless filter paper, recommended for analytical procedures involving coarse particles or gelatinous precipitates (e.g. iron or aluminum hydroxides). Also used in quantitative air pollution analysis as a paper tape for impregnation when determining gaseous compounds at high flow rates. This filter is also available in the Whatman Disposable Filter Funnel. This is a convenient, disposable 47 mm filter funnel with a 250 mL capacity. The 47 mm Grade 41 filter can be easily removed for further analysis or culturing.