This is a stainless steel portafilter ring. It is 51mm. The photo shows it attached to the filter that comes with the Dedica. The portafilter is not included. It prevents coffee grounds from scattering when used with 51mm portafilters, such as those on the De'Longhi Dedica. This is a used item, so please refrain from purchasing if you are concerned about its condition. Thank you for looking.