FM grid stands for Frequency Modulation grid (also called stochastic grid). Both names indicate the absence of patterns in the placement of the grid points, or the total arbitrariness in the arrangement of the points in a plane. The FM grid does not change the size of the grid point, but varies the number of randomly placed grid points per square centimeter. The grid points are so small that even with a magnifying glass they are difficult to see as individual grid points.
The fineness of the grid gives you much more sharpness and contrast in your images than you can achieve with a classic AM grid. This gives your images much more detail and disruptive effects such as the stepped display of straight lines and frayed edges in texts made out of partial colours are a thing of the past.
Due to the random placement of the grid points, no more moiré can occur, unless it is already in the original image of course. Moiré is an undesirable (ring) pattern that arises from the collision of AM grid patterns with structures in the image. The FM grid is therefore ideally suited for printing detailed textile products such as clothing, but also furniture, carpets and hi-fi equipment.
And last but not least, this technique also uses less ink.
The result is an astonishing sharpness you've never seen before.