A shiny end, in many shapes and colors. Aluminium strip has exactly the properties that closures need.
aluminium offer 1060 aluminum strip for injection vial seals since long time ago, because 1060 strip is easy to make and cheap price, in many countries 1060 strip for injection vial is still very common, signi aluminum could offer plain aluminum strip, lacquered aluminum strip, coated aluminum strip in color of golden, white, red, blue, black etc, one sides color, both sides lacquered etc.