Exchange

: A compact, lightweight piece that is priceless for avoiding plastic bag charges, especially in Europe.

If you are preparing for a student exchange trip or long-term travel, certain "pieces" of equipment are considered essential for daily comfort: exchange

Depending on the type of "exchange" you're referring to, the most "useful piece" can range from a historical coin to a versatile travel tool. : A compact, lightweight piece that is priceless

: A critical piece for ensuring you can charge your electronics in different countries. : A compact

: A lightweight piece that dries quickly and takes up minimal space in a backpack.

Is this related to a (like chess) or a historical topic?