The new bottomless portafilter for La Spaziale has a 1 mm spring clip and a modified design that allows insert baskets to easily be fitted in and removed. Included with the portafilter is a precision triple insert basket 21 grams.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 La Spaziale Bottomless Portafilter fits all of the La Spaziale commercial machines, as well as the Mini Vivaldi and the Vivaldi II. This portafilter is cut out by the manufacturer so you will notice the nice chrome finish on the bottom.