Rancilio Vfa Grinder Flat Blades  €21.99

If you can't get the grind any finer, then you need to replace the blades.
Your new blades are sharper and will deliver a finer grind, so you will have to adjust your grinder after you replace the blades.

Size: 64 x 38 x 9 mm
Type: 3-hole, left-hand rotation

Note: It is common for grinder blades to have "spots of oxidation from exposure to air; this does not mean that the burrs are used or inferior in quality in any way.