La Marzocco 6mm Group Head Gasket
This gasket measures 72 x 55 x 6 mm and fits La Marzocco GS-2, GS-3, Linea, FB-70, GB-5 and FB-80. The thinnest version with no bevel, used on newer machines with little or no wear on the groups and portafilters. La Marzocco #L105/B6.
PF locks in right at 6 o'clock. Works great.
I use a 20gm basket with my GS3 MP and find the Porta filter fits better with the thinner gasket. It lasts the same as others, but the ability to get the portafilter more fully seated in the brew head is a pleasure.