The cross section measurements are given as outside first, then inside and finally the height. Because they are flexible, the measurements you may have and those listed may vary slightly, which should be expected. The cross section will often be just proud of the internal dimension of the groove as it uses friction to stay in place.
Occasionally a gasket may specify a 8.2 mm (Pavoni) or 6.65 mm (Spaziale) dimension at the cross section section; though we have generally rounded the measurement to the closest millimeter, we warrant the gasket to be appropriate to the machine.
Most Popular. The most common gaskets are for each machine are noted as [MC]. Because manufacturers would sometimes produce models with different gaskets in the same years and with similar lines it is a good idea to have a few of the less common gaskets on hand. We are listing the most common gaskets in red as an assist, but it's up to you to make sure it's the right gasket for your application.
Cross Sections. Many manufacturers, whether infinite wisdom or simply a desire to be different (likely the later) have slight variations of cross section design. Often several different gasket styles will fit into the same group. Close counts, so long as the portafilter fits well.
Here are some samples of cross sections for various manufacturers: