https://londiniumespresso.com/store/index.php?route=product/product&product_id=313&search=seal Londinium writes: You are purchasing ONE LONDINIUM piston seal (there are three of these seals on the piston) This item will ship from New Zealand by post and is therefore likely to take 4 weeks to arrive to most customers The seals are only 8mm thick so we hope to send them in an envelope These seals have been developed by LONDINIUM in New Zealand to run with very low friction without grease and provide an extended service life for the seal and also the shower screen, and to eliminate a possible source of channelling (a shower screen partially blocked with silicone grease) These seals are not made from Viton, nor are they made from silicone, but the material is certified for use in potable water at temperatures and pressures greater than what our machines can impose on the seals Given you are moving to a no grease seal i recommend that you replace all three piston seals,