A five-coin string takes one coin from each of five Qing reigns and threads them on a single cord. Historically the five chosen were the longest reigns, and the grouping is about continuity rather than magic.
The coins on this charm are brass castings made from traditional moulds. They are explicitly reproductions, with no age and no numismatic value, and the listing says so plainly — a genuine set of Qing coins would be a different market entirely. Short drop, so it is unlikely to obstruct a view.