A retailer buys many identical units at the same cost per unit. It initially sells some units at a price 25% above cost and the rest at a price 10% below cost, producing an overall profit of 11% of total acquisition cost. Later, one-fourth of the units sold above cost are fully refunded, then resold for 80% of cost; each such return also costs the retailer a $6 processing fee. After these events, overall profit is 2% of total acquisition cost. In a counterfactual, instead one-third of the units sold above cost are fully refunded and resold for 90% of cost, with the same $6 fee per return.