Canning jar bands are not made to last forever- they will eventually rust so replacements are always a good thing! To ensure a long life of your bands, be sure to wash by hand and dry them well after each use.
Wide mouth bands measure 3 1/4 inches round. (fits 16, 24 and 32 ounce wide mouth jars)
Regular mouth bands measure 2 3/4 inches round. (fits 8, 12, 16, 32 ounce regular mouth jars)