One of the two unit of measure modes you can select when you turn unit of measure on.
When you select Multiple U/M Per Item as your unit of measure mode, you can create any number of units of measure—called a unit of measure set—for a particular item. This is especially useful for inventory items that you buy in one unit of measure and sell in a different unit of measure. For example, you might buy candles in boxes of 12 but sell those candles individually.
When you create a unit of measure set, you specify which units of measure should be used where in QuickBooks. For example, you specify which unit of measure should appear for an item on a purchase form and which unit should appear on a sales form.