A bottomless portafilter by Nuova Simonelli. The Nuova Simonelli Bottomless Portafilter originally started out as a spouted portafilter. Included with the portafilter is a Nuova Simonelli double insert basket.
What is a bottomless portafilter and what is it used for?
Bottomless portafilters are used as a training tool. 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.
The Nuova Simonelli Bottomless Portafilter fits their commercial machines, such as the Aurelia and the Appia. Also fits the Oscar and Musica.