This qualitative filter paper has a diameter of 7cm and retains medium sized particles. Our qualitative filters average .15% ash content. Our filter paper is produced in circles and sized by diameter. Each pack contains 100 filters. Quantitative filters are used when you are generally concerned about what is left on the filter. Qualitative filters are used for both collecting a precipitate or solid and removing unwanted substance from your filtrate that passes through the filter, but not as concerned about he quantity of substance that remains on the filter. Sold in packs.. These are new and unused.