A "wu shi" plaque is deliberately plain: a blank, polished rectangle of wood with only a cord hole at the top. The name is a play on words — the same characters usually mean "without incident" or "nothing to report," so an empty plaque is a way of saying "may nothing happen."
It is one of the few Chinese decorative forms that is genuinely minimal, which is why it sits well in a modern car interior. Rosewood, polished but not lacquered. The tassel is silk; trim and re-knot it if you need a shorter drop.