Single Rubber Grommet for use with Airlocks Rubber Grommets are used to hold securely hold airlocks in brewing bin lids and demijohn lids £0.75 Rubber Grommet Options: [Choose]Black Flat O'ring Style GrommetsRed Cone shaped Grommets (+£0.20) Quantity: at £0.75 each Add To Basket 27 in stock.