Non-sterile gridded Cellulose nitrate membrane filters by Whatman. Recommended for the majority of routine applications, this grade is manufactured under strictly controlled cleanroom conditions. Can directly replace the general purpose membrane filters of other manufacturers without requiring any significant change of technique. Other benefits and features include: Improved strength and flexibility to tolerate abuse without sacrificing integrity Low extractable levels—approximately 2% Autoclavable at 121°C (250°F), with low shrinkage. Can be heated to 130°C (266°F) without damage. Can be autoclaved two or three times without major changes in physical properties. Gridded surface (3.1mm intervals) make filters ideal for colony counting after incubation. Special non-toxic ink used is completely free from bacterial growth inhibitors. Pore Size: 0.45µm. 100/Pack. Whatman #: 7141-004.