Bialetti Replacement Rubber Seal for 4 Cup Brikka Espresso Maker bialetti original replacement rubber seal/ring/gasket suitable for the 4 cup brikka aluminium espresso makers. outer diameter approximately 7.0cm/2.8in - inner diameter 5.4cm/2.1in. loose packed. cup size is based on espresso cup sizes and not on regular tea or coffee cup sizes.