Brand: Rancilio Color: Black/Silver Features: Naked Portafilter for Rancilio Silvia machines - Size 3 Cups - 21 grams It will provide you with immediate feedback and can see if channeling occurs right away Bottomless portafilters are used as a training tool Group Head Size 58 millimeters Ergonomic Handle Details: Fits all E61 groupheads. What is a bottomless portafilter and what is it used for? Bottomless portafilters are used as a training tool, They have been produced either by the manufacturer or sent to a machinist to have the spouts removed. The bottomless portafilters all come with a triple insert basket. It will provide you with immediate feedback and can see if channeling occurs right away. Channeling is the rapid passage of water through fractures in the coffee puck, which produces a thinner, under-extracted espresso. When it occurs, you'll often see sudden appearances of blond streaks in the stream of espresso; sometimes the puck will even have pencil lead-sized holes where channeling occurred. UPC: 735343242120 EAN: 0798527559247 Binding: Kitchen Item Condition: New