This 58mm Bottomless (Naked) Portafilter is designed to work with the Breville BES900XL, BES920XL, BES980XL, BES990BSS Dual Boiler Espresso Machine.With this bottomless portafilter 58mm, youll be able to see the extraction in real time to understand if youre grinding and tamping correctly.Detachable design, convenient and quick to disassemble, easy to use, and easy to clean.BASKET NOT INCLUDED - If you want to improve your barista skills by using a visual aid to identify what youre doing wrong, this is the perfect tool.What is a bottomless portafilter and what is it used forBottomless 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, youll 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.With this 58mm naked portafilter, youll be able to see the extraction in real time to understand if youre grinding and tamping correctly. If you want to improve your barista skills by using a visual aid to identify what youre doing wrong, this is the perfect tool.Color: black + silverMaterial: Alloy + PlasticSpecification:Item Type: 58mm Bottomless PortafilterWeight: 0.73lbPackage Contents:1 x 58mm Bottomless Portafilter (BASKET NOT INCLUDED)Note:Only compatible with the Breville BES900XL, BES920XL, BES980XL, BES990BSS Dual Boiler Espresso Machine.Only the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.