Vintage Clear Kerr Embossed Self Sealing Glass Normal Mouth Half Pint 0.8 Oz Mason Fruit Food Canning Preserving Jar Drinking Glasses 1 Cup K#6 This jar has writing for Kerr, "SELF SEALING", and MASON. Alexander H. Kerr founded the Hermetic Fruit Jar Company in 1903 and among the first commercial; products were the Economy and Self Sealing jars. They also incorporated aspects from two 1903 patents held by another inventor, Julius Landsberger: a metal lid with a permanently attached gasket. This made the lids easy to use and inexpensive. 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.