ECM Bottomless / Naked Portafilter

An exposed portafilter basket more clearly shows the extraction process, a great way to diagnose any grind, distribution or tamping issues. They are also easier to clean as they do not have spouts. Some would argue the flavour is better as the coffee does not pour over metal before going into your cup.
Bottomless portafilters are excellent for fitting taller mugs or glasses under your coffee machine group head.