Flat rubber portafilter disk insert for domestic/home espresso machines. This soft rubber disk is designed to be placed inside the portafilter basket for use in backflushig/cleaning. It blocks the holes in the busket so the water is flushed back through the machine. It fits most espresso machines although it works better in baskets with a flat base (most double-shot baskets). If your espresso machine already has a stainless steel or blank disc this rubber disk is not required. This is only required if you have an espresso machine with portafilters but no means on blanking the baskets. *does not include portafilter.