Viton O-Ring for Steam Valve & Mushroom Assemblies This Viton (FKM) o-ring seals the lower mushroom on Brasilia, ECM and VBM group heads, and does double duty on the steam valve body for Gaggia and La Spaziale machines. Viton's heat and chemical resistance make it the right compound choice anywhere it sees repeated exposure to hot water and steam. SPECIFICATIONS 2.62 mm thick, 20.63 mm ID (O-Ring 0128), Viton/FKM COMPATIBILITY Fits: Brasilia, ECM, VBM lower mushroom assemblies; Gaggia, La Spaziale steam valve bodies INSTALLATION Simple o-ring swap, lightly grease with food-safe silicone lubricant before seating so it isn't pinched or rolled during reassembly. PRO TIPS Don't substitute a generic NBR/Buna o-ring in this size just because it fits, Viton is rated for the higher sustained temperatures a steam valve sees, and a Buna substitute will harden and crack within a season.