The inner diameter of the Non-pressurized Porous Filter Basket is 51mm, which is generally applicable to for 51mm Bottomless Portafilter. some 51mm Portafilter of original standard may not be deep enough to insert the Filter Basket. It is strongly recommended that you carefully measure the inner diameter and depth of your Portafilter purchasing. The product contains 3 filter baskets and a blind filter. The depth of 4-cup Filter Basket is 36mm, the depth of 2-cup is 25mm, the depth of 1-cup is 19mm, and the depth of Backflush Blind Filter is 14mm. The product made of stainless steel is safe. It is very easy to clean and convenient to use for the time. The product is slightly magnetic, allowed to connect to magnetic Dosing Funnel. Please read the product information carefully buying, Colour: silver Material: stainless steel Package Contents: 1 x Single cup 1 x double cup 1 x 4-cup 1 x Blind Cup 2 x Brush Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.