Kilner jars were originally made out of a glass plug which had a rubber close, which was kept in position with a metal screw-top cover. Today, is has been replaced using a rubber-rimmed metal seal and a separate screw-top lid, but the airtight qualities - allowing the contents to remain fresh for months, in any other case years - have not been compromised.Are You Looking For Jam Jars?Home-Made Natural and organic Ice-CreamKilner Jars