Caffeewerks’ colorful silicone gaskets outpace their rubber counterparts in flexibility, consistency, and longevity. The soft silicone gasket is designed to create a seal when the portafilter is locked at the 6 o' clock position so that you don't need to over-tighten. This keeps the grounds from impacting the shower screen and prevents burning the flavor out of your coffee before extraction. The silicone is softer than rubber, making for less pressure on your wrist and portafilter as it creates a seal in the group. The green gasket is compatible for use with espresso machines from the following brands: Rancilio Silvia M Rancilio Silvia Pro Rancilio Silvia Pro X Rancilio Commercial Espresso Machines