Gaggia Silicon Gasket x 2  €8.99

This contains 2 heat-resistant silicone gaskets and paper shim in case portafilter slides to the right. Silicon lasts longer, this makes a big difference in busy environment.
The internal groves and soft consistency make for easy installation and removal and the light color helps to detect if there is a build-up of coffee debris 

If you notice that there's water leaking from the area above the portafilter, known as the group head, then your gasket is probably to blame. When changed your coffee cream will improve as you will have achieved the maximum extraction pressure of 9 bars. (The pressure will be constant as the filter basket has a full seal.)

Features:

• Better than rubber gaskets, since silicone doesn't have any smell or taste and is easy to change in and out.
• The light color helps to detect if there is a build-up of coffee debris.
• Easy to install - just push on and lock with the portafilter.

Gasket change:

• Commercial: replace every 6 months,
• Home: replace every 12 months 

The longer you leave it the more difficult it will be to remove them. The group seals become brittle over time due to heat from the portafilter and with age. When removing the old one it will probably fall apart as it will be so brittle. We recommend that you always keep spare gaskets.

Search terms:

Gaggia classic Silicon Gasket, 8F403S