A coin flip is the small two-by-two-inch inert plastic holder used by collectors to store individual raw coins. Despite the name, the safe versions are mylar or polyethylene rather than vinyl — vinyl flips contain plasticisers that leach onto coin surfaces and cause irreversible green slime damage over years of contact. Mylar flips are inert, archival, and standard issue at every major coin show.

Flips are typically stapled along three edges, with the fourth left open to slide the coin in. The coin sits between two transparent windows so both obverse and reverse remain visible. A separate paper insert behind the coin records attribution, grade, source and price paid. The flip-and-insert pair is the most common bulk-storage format for raw coins among serious collectors.

Beyond the obvious meaning of a physical flip to determine an outcome, coin flip in collector contexts refers to the small archival paperboard holders — typically two-by-two inches — used to hold individual coins for storage and trading. The cardboard holder is folded in half around a clear plastic window that displays the coin while protecting it from handling. Coin flips are stored in long boxes designed specifically for the format. See our slab entry for the encapsulated storage option used at higher value tiers.