The Idea Of Knock Box Is Simple: It is a nice container that has a bar across the middle. You simply bang the used portafilter on the bar preventing the filter from popping out and let the coffee grind cake fall into the container. Our DIBTSA knock box is perfect for this. It is about 8.58 by 6.25 by 4.13 inches in size. It holds a lot of coffee grinds, at least 30 brews. The bar has a rubber surround which makes for a soft hit as opposed to metal on metal, reduce noise and protect your portafilter Well Made Knock Box: The rubber covered knock bar keeps noise to a minimum but can withstand some pretty hard knocks for the stubborn puck . The stainless steel box rests on stable rubber feet that protect your countertop. The bar lifts out when you need to empty the box at the end of the week Non-Slip Design: This knock box is surprisingly sturdy and grips the counter top perfectly ! The rubber suction on the bottom and weight of the box keep it in place even when knock the grinds with great force Easy To Clean: Clean up is simple as you just take the bar off, since it in the sink and dump the coffee in the garbage. A paper towel might necessary to wipe out any remaining coffee grinds at the bottom Package Includes: one knock box with one knock bar Espresso Knock Box, DIBTSA Coffee Grounds Pucks Knock Box with Removable Rubber Knock Bar and Non-Slip Base ( Matte Black )