Jar, Keeran developed the Eversharp mechanical pencil.

The lids are made of metal with a ring of sealing compound which acts as a gasket against the jar's rim. Lids may not be used more than once. Older unused lids should be discarded, as sealing compound is only good for about five years from date of manufacture. New lids are slightly domed (convex). During processing, air is vented from the jar and the food shrinks. While cooling, a vacuum is created inside