This replaceable rubber gasket forms a tight seal on the closures of glass wire bail (clip top) storage jars with 4"Dia mouth openings. For use with 3-litre Kilner wire bail (clip top) round storage jars, as well as other brands of similar jars having 3¾"Dia mouth openings.Pack of 6Size: 4"Dimensions: outer: 4¼"Dia; inner: 3-3/8"DiaMaterials: RubberProduct of ChinaBefore use for preserving, it is recommended that gaskets first be sterilized in boiling water; use jar tongs to remove gaskets from boiling water.