Glass fiber filter, round, SiO2, Grade QM-B, 42 mm, 50 pc/PAK

Whatman quartz microfiber filters are made from high purity SiO2 for processing air samples in acidic atmospheres, any application with temperatures up to 500°C and for PM-10 testing. Due to the low levels of alkaline earth metal impurities in the product, sulfate and nitrate contamination is virtually eliminated.
QM-B filters are similar to Cytiva's standard QM-A quartz fiber filters, which are recommended more commonly for air testing applications. By comparison, QM-B is approximately twice as heavy, twice as thick, and offers slower flow rates.
Because of these characteristics, QM-B can be used in air monitoring applications requiring increased strength or durability.

You may find the certificate here: https://www.cytivalifesciences.com/en/de/support/quality/cer tificates