Prior to canning innovations of the 19th century, pickling jars were often sealed with animal bladders. Animal bladders are difficult to come by and unpleasant to work with. These imitation bladders provide an authentic look and effect without all the squeal and unpleasantries. Each package contains 4 - 12" by 12" sheets which will seal 4 large crocks or 16 small mustard jars. To use soak sheet in warm water for 10 minutes and tie on to jar.