Quantitative Grade, Ashless
| Grade No. | Flowrate | Retention microns | Wet strength | Thickness, mm | Ash % | |
| 43 | Intermediate retention and flow rate between Nos.40 and 41 | Medium/Fast | 16 | Low* | 0.21 | 0.01 |
*Suitable for gravity or low suction filtration. Care must be taken to prevent rupture of the paper.