o ring seal for 4 inch wine fermenter cap

Tony's Tips,

this 4" seal is not to be confused with 4" Beer or Cider Barrel Cap Seals - (different cross section). but either seal, different as they are, will benefit from a light application on all sides with specially formulated, Pressure Barrel Seal Grease available from Balliihoo to ensure a good airtight seal with no fear of Contaminating the brew.