1.9 mm thick, 7.2 mm internal diameter. For one application, the o-ring is used for the VBM steam and water wand swivel o-ring.
Faema: this was only used in the old version E91/Due steam valves (ca., 1991-1993), pictured in the diagram behind the valve rod bushing. If you are unsure which version you have, note that in order to access this o-ring you have to remove a small c-clip out of the valve to get the valve rod out. If your valve doesn't have this small c-clip, it is likely you are looking for this o-ring instead.
ECM: used on the steam and water valves shaft.
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.