Bottomless portafilters allow the barista to visually assess how evenly the coffee extracts through the basket. This bottomless portafilter or naked portafilter fits the espresso machines. It comes with the 3 shot 21g filter. It helps to control and diagnose the extraction of espresso shots and assures a pure espresso with a great crema. It’s an amazing espresso accessory for training because channelling will show you, that the coffee ground is not properly compressed, or it just guaranties a perfect show.