Vacu-Seal Mason Canning Lid
Canning lid, metal, gold colored on onw side with rubber seal on back and off-white color.
-Per the web site (see also object file) http://www.pickyourown.org/canningjars.htm 12.13.10:
...Mr. Kerr later (1915) invented a smaller, flat metal disk with the same permanent composition gasket. The lid sealed on the top of a mason jar; a threaded metal ring held the lid down during the hot water processing. This allowed re-use of old canning jars together with inexpensive and easy to use disposable lids. The jar we know today was born! This two-part lid system transformed home canning safety and is still in use today.
Kerr also made the first wide-mouth jars, which Ball was quick to duplicate.