Cafelat Silicone Group Gasket - 8.3 mm Nuova Simonelli
71 mm x 56.5 mm x 8.3 mm (Red) conical, for all of the older models of Nuova Simonelli, including the Program, Optima, Personal, Program VIP, Premier, Premier Maxi, Mac Digit, Mac Cup, Mac 2000, Oscar, Oscar II, Musica, Appia and Appia II. Newer models such as the Aurelia use the Blue version. The Cafelat and "NS 2" side faces up when installing.
Some product history and notes:
Works well in my oscar1.