A thick glass jar with a threaded neck and a two-piece lid, a flat disc with a rubber-like seal held down by a screw band, made for home canning. During processing the lid vents air, and as the jar cools the seal is pulled down and the disc clicks concave, which is the sign of a vacuum. The name comes from John Landis Mason's 1858 patent and now covers canning jars generally; Ball and Kerr are the common American brands, Kilner the British clip-top equivalent.
Beyond preserving, the jars are standard for pickling and fermenting vegetables, soaking oats, storing dry goods, shaking salad dressings and serving drinks. Canning lids are single use; the bands and jars last indefinitely if the rims are unchipped. Jars sold for storage are not always tempered for a boiling-water bath.