After that it could buy emissions credits from Germany for the price "P" (per unit). The internal cost of Sweden's own abatement, combined with the permits it buys in the market from Germany, adds up to the total required reductions (RReq) for Sweden. Thus Sweden can make a saving from buying permits in the market (Δ d-e-f). This represents the "Gains from Trade", the amount of additional expense that Sweden would otherwise have to spend if it abated all of its required emissions by itself without trading.