73 mm x 57 mm x 8.75 mm suitable for all variations of the E61 group, this is the thicker for worn groups and/or portafilters where the portafilter locks into place too far to the right. The "REPA" and dimensions side faces up when installing. Some product history and notes: The reason silicone was chosen as the material is purely from a cleanliness point of view, the gaskets are neutral and do not have any smell or taste They do not bake hard so removal is easier No need to crank the portafilter tight in the machine as you would a hard EPDM rubber (the industry standard) gasket Always use a silicone lubricant such as food safe white grease. Silicone does not like petroleum based grease When installing do not use a sharp screwdriver to push them in, the silicone will break. Use the portafilter with the basket removed to install