Astoria 58mm silicone group gasket
Please note that although the gaskets are strong under compression, you should never use a sharp tool like a screwdriver to install them. This may tear the silicone.
This is the standard Astoria group gasket for 58mm groups. The original mfr. part code is 12217 - this is the same as that.
Size for Astoria 58mm gasket: 72mm x 56mm x 8mm (Blue colour): SGS food test report
This does not fit the smaller 53/54 Astoria groups.