Coffee grounds can get stuck in the portafilter after making espresso. To relieve this problem, we offer an espresso knock box, which you can use to knock the used coffee out of the filter. Knock boxes keep all of the used coffee in one place, so it can be recycled. Additionally, this product comes with a removable knock bar that you can use to clear your espresso filter. If you’re looking for additional espresso accessories, check out our espresso cups. We also have a large selection of bulk coffee and espresso, and espresso machines. If you're wondering where to buy knock boxes, we have a large selection of knock boxes for sale at the lowest prices.