The lever system of this professional coffee machine allows you to manually modulate the pre-infusion for each batch. When you lower the lever, hot water from the boiler soaks the coffee. The more the barista pulls the lever, the longer the pre-infusion phase. A good professional waits for the first drops of coffee before lifting the lever; this means the water has infused all the coffee. For an effective pre-infusion, the water pressure should not exceed 2 bar when entering the group.