This is a spart parts compatible for Delonghi 51mm coffee machins and SMEG ECF01. This Gasket is used on many models of Delonghi espresso makers. The Gasket is made of a high temp silicone and is used to create a seal between the diffuser and the filters. If water, steam, or coffee leaks out of the filter while brewing then this part should be replaced. To replace this Gasket first remove the diffuser by removing the screw. Then, gently pull the old gasket off. Clean the area with a damp cloth. Install the new Gasket and reinstall the diffuser.