All MILKFOR polypropylene filters retain 100% of milk fat content, because the size of milk nutrients, including the largest fat balls, was taken into account during their development.
In size, they reach 15 microns. Inasmuch fat balls retain elasticity in warm milk, they freely pass through filter channels of the same size.
However, other manufacturers may have filters available with a milk purification level of less than 15 microns. Such filters decrease milk partially or completely, which has been proven in laboratory conditions.