Before Rubbermaid, even before Tupperware there was the glass container for left-overs. These 6'' x 2 3/4'' containers have plastic lids with "left-overs'' across the top, to leave no room for error. The seal is less than air tight, but was the choice of the time. These older pieces are in great condition and are unmarked.
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We're heading south until January 31, but will be shipping again on Feb. 1st.