Bialetti Replacement Rubber Seal for 1 Cup Cuor di Moka Coffee Maker Pot Loose original bialetti replacement rubber seal/ring/gasket suitable for the bialetti 1 cup cuor di moka coffee maker. outer diameter 5.1cm/2in - inner diameter 3.3cm/1.3in. loose packed. cup size is based on espresso cup sizes and not on regular tea or coffee cup sizes.