La San Marco #109252 (CTSORI0150).
3.53 mm thick, with an internal diameter of 55.25 mm. Group to boiler o-ring found in the models:
Serie new 105 multiboiler Gruppo multiboiler completo
Brewing Group 20/20 P&P Brewing Group
Delivery unit 85 Flexa-E Delivery unit
Brewing Group D. MB D. Brewing Group D. MB
Coffee unit SM MINI Coffee unit
Coffee unit SM 1 Coffee unit
Coffee unit SM 2 Coffee unit
Capsules and Boiler Group WE2 WE2 Capsules and Boiler Group WE2
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.