Ensure accuracy while eliminating the inconvenience of preweighing filters by using preweighed, preloaded filter cassettes. Preweighed filters meet the methods for gravimetric analysis requiring filters to be weighed both before and after sampling. Each filter, equilibrated to 68°F (±1.0°F) and 50% (±1%) relative humidity, is weighed using a high-accuracy microbalance to within 0.00001 g. Once weighed, filters are placed into the cassettes and sealed with a red band indicating the weight and a unique serial number.

Since the environmental conditions can have a significant effect on filter weight reading, post sample weighing should be performed under the same environmental conditions. Model 60061-50 with a security band provides the reassurance of tamper resistance.