The Tubbi is extremely tough and resists well to knocks from the portafilter thanks to plastics that flex a little. The food safe rubber bar is reinforced with stainless steel. A non-slip rubber pad on the bottom prevents it moving about the place and also helps to reduce the noise. The knockbox may be small but it can comfortably hold 15 double pucks of coffee before it needs emptying. To empty, just lift the rubber bar out and discard the coffee!