Designed to fit 54mm Breville Portafilters and also BES870/875/878/880 portafiltersFunnel attachment for the portafilter prevents messes by preventing the coffee grinds from overflowing and spilling around when grinding or tamping your brewTwist the funnel onto the portafilter and insert it into the grinding cradleAfter dosing your brew, you can tamp the coffee grinds while the funnel is attached to save time