The numbers associated with each purify filter indicates the number of microns between each pore of the filter:
-25 microns (µ) is a super fine pore size, best for straining pollens and more fine particles
-73 µ is for a finer tincture and better clarity—removes more plant residue from alcohol
-90 µ is for tincture and captures even finely ground sediment—for thin consistency of alcohol
-190 µ is ideal for use with cooking oils and makes the process a breeze
-220 µ is a larger pore size, great for butters and thicker extracts
