This filter is for Chemex 3 cup only. [Features] The "CHEMEX Filter FP-2 for 3 Cups" is a Chemex 3 cup filter. It is 20-30% stronger than regular filters, so it removes the cause of dirt and extracts the original taste of your coffee. The Chemex Coffee Maker was invented in 1940 by a chemist, Dr. Peter Schrambourm.