Ball Mason Jar Lids
Mason jars typically have 2 size lids: regular mouth (70mm) and wide mouth (86mm)
Ball jars come standard with a 2 piece lid consisting of a flat disk which has an inbuilt seal (the lid) and a separate screw band (the band) which holds the flat lid in place during heat processing.
One piece metal lids can replace the 2 piece lid for heat processing. Plastic lids are strictly for dry storage and preserving processes that do not involve heat.