The Solis Coffee Knock Box is an indispensable accessory for your espresso machine. You can beat the used coffee in this container. With one knock on the crossbar, you can easily knock the used coffee out of the filter holder. You can then easily check whether the rest coffee is dry. If the coffee is not dry, the machine is not set correctly. After use, you can remove the crossbar and wash the knock box by hand or put it in the dishwasher.