The name Sifdis comes from the two words "sift" and "distribute". It is a small hand operated device created to declump and evenly distribute ground coffee into the portafilter basket. It is made of four pieces of canvas phenolic and one piece of stainless steel screen. It has a lip on the bottom to sit on top of the filter basket while the top "gear" is spun pushing the coffee grinds around and through the screen to evenly distribute them.
The inside diameter of the entire assembled Sifdis is equal to the inside of a standard filter basket, ~58mm. The total outside diameter is 2 7/8" and the overall hight is 2 3/8".