 Some of these "Elm Seed" cash coins were as small as 10 millimeters in diamer and weighing only about 0.4 gram.Some privately produced Ban Liang cash coins had the Chinese characters for "twenty" (二十) incused or engraved above the square centre hole.Current speculation on this variant is that numbers like this did not in fact refer to the "value" (or denomination) of the cash coin, but that these numbers would rather refer to some still unknown "quantity" or "measure".