- 54mm Naked/Bottomless Portafilter head designed to be compatible with Breville the Barista Express, Barista Pro, Barista Touch, Bambino Plus, Infuser and Duo-Temp Pro. - Extraction improvement: Use a 54mm bottomless portafilter to clearly see what's happening under the hood, identify and correct extraction problems such as grind size or tamping errors. Great for beginners and experts. - Ergonomic design: Portafilter handle made of natural sandalwood for a secure grip and easy manual control; portafilter head cast in food-grade stainless steel and hand-polished; precise size ensures the portafilter engages with the group firmly. - Important fit note: Our portafilters are designed to fit snugly into the espresso machine group head, providing a tight seal when brewing. However, due to tolerances between machines, some may fit more snugly than others. If you experience fitment issues, please contact our team directly. - Use scenarios: Troubleshoot grind and tamping by observing flow in real time; validate changes in grind setting or tamping pressure; compare extraction behavior across different Breville models or doses.